The condensed version of this review is as follows:

Man bows the shit out of a guitar for two hours. Audience leaves happier than they entered.

Wembley seemed like it could produce a nice challenge for Sigur Rós - given the fact that their music looks to strike you personally, and works very well in a smaller space or outdoor venue, how would they cope with Wembley Arena's rather barren canvas? Luckily for those of us who made it, the Icelandic troupe managed to make their music intimate when it needed to be, and ear-gougingly sonic at just the right moments. There were times when the music would quieten down, and you could hear everyone round you, and the sound of someone cheering would carry down the whole arena - it was as if Sigur Rós had performed some sort of shrinking charm on the whole location, and it really made the atmosphere play towards the band's strengths.

No matter how Sigur Rós coped with it, I Break Horses managed to complete nail their five-song set, acting as the opening band. Their shoegaze tinged indie may have felt a little out of place a year or so ago, but they seem to be driving forward to new, glitchier heights, a lot more positive in their drive to make themselves a band you deserve to know about. With their new album, Chiaroscuro, due out in January, there were some new tracks played, as well as the two hit killer punch of 'Hearts' and 'Winter Beats' rounding off their set. 'Hearts' played out exactly as you'd hope it would, swelling and breaking in a cacophony of noise. The new tracks definitely brought to mind early The Knife, at the period of time when they were certainly experimental with their electronic output, just not to the far extents they are now. It was really great to see, and I Break Horses have no doubt earned themselves a number of new fans over this past tour spot. There was one incredibly bizarre thing about their performance, which probably didn't spoil it, but certainly left a weird taste in everyone's mouths...

You will probably recognise from Sigur Rós gigs the giant curtain put down in front of the band, which sometimes stays for the duration, or sometimes goes after a few tracks. Throughout the whole I Break Horses set the curtain stayed down, and although it was a relatively nice effect (there were only the three people on stage, and few lighting effects going on) it felt really impersonal, and a little out of place. My main concern about seeing I Break Horses was that their music wouldn't come across as human, and luckily their music did. There was just this big old curtain over them for the whole thing, which ended up disappearing three songs into Sigur Rós' performance anyway. I couldn't help but feel sorry for any photographers wanting to take some shots of the band, faced with this interesting challenge. Curtains aside (ahem), you'd struggle to find anyone from the show who wouldn't be at least a bit more curious about the band after their set.

By the break, the arena itself was starting to fill up more, but it never felt completely full, even when Sigur Rós took the stage expectedly promptly. The band kicked off with 'Yfirborð' a song that seems to have evolved consistently over this tour, and felt a lot more buoyant and 'cheery' than it's album release. We then were treated to 'Untitled 1' ('Vaka'), and it's here, early on, that a couple of thoughts entered my head.

Firstly, 'Untitled 1' was rendered beautifully. It was a wonderful surprise near the start to have something which completely forced you to take your guard down. It's certainly never been an understated song, but it never explodes unnecessarily, and demands your attention without making it seem like it's grasping for it, hopefully. Secondly, it was hard to imagine how a band like Sigur Rós pull off one particular feat. So many of their songs are wrought in such passion and feeling, that playing these songs on a long stretch of touring must completely emotionally drain these guys. Unfortunately, for ourselves, there were little cracks that started to appear every so often that perhaps showed these qualms.

Glósóli has all the hallmarks of a show stealer, but it had a rough start where the percussion loop seemed to be repeating an oddly mistimed bass note. It seemed to remedy itself near the middle of the track, but it just felt a little off. There were peppered throughout the show these small indicators, a little cough here, the odd glance between the performers at missed beats - it was uncharacteristic, and I guess it didn't really effect anything too much, the quality of the music was still there, sure. The worst thing that can be said, I figure, is that you just weren't getting Sigur Rós on one of their 11/10 days.

The setlist itself was pretty special; there was a weighting in favour of recent release Kveikur, but a number of tracks from ( ) made an appearance too. Including the aforementioned 'Untitled 1'', with 'Untitled 6' ('E-bow') and 'Untitled 8' ('Popplagið') also joining the ranks, 'E-bow' itself was one of the highlights of the whole night, and along with the other tracks from ( ), reinforces how important that album is as a hallmark of post-rock done right, without compromise. From Valtari, we only had the one track, 'Varúð', which was one track you'd imagine the band indulging more than they did, cutting the track shorter than, at least, myself would have liked. 'Hoppípolla' was played alongside its brother 'Með Blóðnasir' (the latter of which I struggle to take seriously, given it's translation 'I Have A Nosebleed'). 'Hoppípolla' received a lukewarm reaction, oddly, and it was an odd performance of the song. The visuals accompanying it were celebratory, fireworks exploding, but the band seemed held back, and this feeling was also felt with 'Festival', perhaps even more so. These weren't sad renditions of the songs, and they weren't played half-heartedly, but they took on an almost tragic vibe, set against 'Kveikur', 'Rafstraumur', and they all paled heavily in comparison to 'E-bow' which kicked off this bunch of songs. 'E-bow' also had some excellent visuals, convincing you the stage was rising, as the backdrop scrolled down over the band as they played. The visuals for the whole event were expertly done, and even if you went in to the gig with an idea of what you thought you were in for, there was something there to surprise anyone. From 'E-bow's' floating effect, to 'Vaka's' music video snippets playing on screen over the performance, and 'Untitled 8's' closing thunderstorm of visual power, you couldn't come away saying you hadn't at least seen something incredible.

'Sæglópur' had a rather solid showing. It has the honour of being the single following 'Hoppípolla', so generally is the song which displayed to casual listeners what else the band could do. So as the opening notes played, it was clear to see this track meant a lot to a number of people. The rarely played 'Ágætis Byrjun' made an appearance, introduced as a song they hadn't played in a long while. This may have been the case a few days ago (it had been years since they last played it live at all before then), but they have played it before on their UK dates this tour. It was still a special appearance, and being followed by 'Sven-g-englar' only increased the nostalgia feels on offer.

Again, the whole idea of Sigur Rós having to tread this emotional line every night reared its head in 'Festival', as the track started with the other band members leaving the stage, leaving Jónsi on his own, playing the song's introduction. There were various points during the song where Jónsi held the high notes for what seemed impossibly long times. Sure, the first time this happened, it was particularly impressive, garnering applause mid-note. The second time, the sound was met with as much clapping as nervous laughter, as you had to wonder just how often this guy has to put himself through the ringer to produce performances like this, and just how much you can assume is completely genuine. The optimist in me says that, sure, fuck, he's a talented guy, and a credit to post-rock, he can completely route himself in the moment. The cynic in me crept out even when 'Untitled 8' came on and I wondered just how a band who play this song at near-on all their concerts can still feel the same emotion, still use the same energy, every single performance, without it harming their longevity.

I hadn't realised just how many people were aware of the band's habit if using 'Untitled 8' to end sets, and so when the track started, I was surrounded by as much groaning over the show's slow climb towards it's finish, as those who exited the arena quietly. It's clear to see why it's used - melding the delicate noodling of 'Ágætis Byrjun'- era tracks with a fragile middle part which crashes in on itself at the end - it's a track which sums up the bands scope. It's become quite a scope in the last few years, and for me it looked like Valtari was going to be a return, of sorts, to their early routes. Kveikur saw to that, by being a whole different beast entirely, a lot more industrial, cold, steely. It makes for an interesting set-list, when you get a variety of tracks from nearly every album (sorry Von fans, no 'Hafssól'), and there is a lot of variation in there.

Had Sigur Rós completed their task when the show ended? The answer has to be that you believe they did, it's just you can't really be sure what that task is these days, it's as unclear as ever. I'd like to say that this is an exciting part of Sigur Rós' future, but the honest truth is that it's hard to know what's next for the band. This never really mattered in the past, and it certainly would never bother the band, but the one thing which stuck out more than anything about this gig was the fact that these guys are playing such an eclectic mix of songs, and going through so many different phases of emotion, just where do we draw the line upon which we say, 'Okay, that's what Sigur Rós do'. That's not a question you would have asked a few years ago, but now more than ever we have a band who want you to cry one minute, and celebrate the next, and with their new material, the outlook is as confused as it ever has been.The truth is, this didn't seem to matter to the majority of people on the night - we had songs performed, on the whole, wonderfully, one after another. And sure, if someone asked me to describe Sigur Rós, I'd probably still say, 'Oh, a bunch of Icelandic dudes who play post-rock. One of them sings really high, and occasionally in a made up language, and they use bows on their guitars. It's cool, check out ( ).' I'm certainly along for the ride wherever they go from here, but I've got a feeling this could be the last time I would see them live, and I'm both happy and sad for knowing that.