Ashton Kutcher doesn't have the best track record when it comes to romantic comedies.Wait, I take that back. Putting a word like 'best' in a sentence that describes a large portion of Kutcher's filmography is being way too lenient. One could actually argue his contributions to the genre — Just Married, My Boss's Daughter, What Happens in Vegas, Valentine's Day and Killers are a more inhumane form of torture than waterboarding.

But to be completely fair, all of those movies would still be unwatchable train wrecks even if Kutcher was nowhere to be found in them. The former star of TV's That 70s Show is not a horrible actor by any means, he just seems to suffer from a bad case of Nick Cage-icitis whenever he picks his films.

It appears, for once, he has finally taken his medicine.

I know, I can't believe I am saying this, but Kutcher's latest vehicle, No Strings Attached, is actually one of the most amusing romantic comedies I've seen in a long time. However, just as Kutcher was not the primary cause of his previous projects being complete disasters, he is also not the predominant reason No Strings Attached works at the level is does. That distinction goes to his co-star Natalie Portman and first-time screenwriter Elizabeth Meriwether.

I don't mean to take anything away from Kutcher's performance because it serves the movie well, but he is simply overshadowed by Portman, who shows a humorous side of herself that we rarely get to see. And it's a side we will hopefully get to see more often.

Portman is getting plenty of attention and praise right now for her Golden Globe-winning turn as an anxiety-filled ballerina in Black Swan, and deservedly so, but her performance in No Strings Attached is the one that is more surprising. Not better, mind you, but more entertaining. Portman, who displays great comedic chops and timing, plays Emma Kurtzman, an emotionally detached doctor in residence who has a self-professed peanut allergy to relationships. Emma doesn't want someone who will wake up with her the next morning and have breakfast, all she longs for is a companion who will come over at 2 a.m. to, well, you know.

That is where Kutcher's Adam, a production assistant on a Glee-type television show, comes in. Through a series of priceless vignettes that spans 15 years, we learn Adam and Emma have a fleeting history with each other, but it isn't until they meet up in Los Angeles in their late 20s that they make the deal of a lifetime.

Adam and Emma agree they will use each other for sex whenever their libidos get out of control (which is quite often), but they make a pact that they will call everything off the instant one of them starts to have real feelings.

Where the movie goes from here should be painfully obvious because, after all, 99 percent of romantic comedies follow an identical formula and end the same way, but Meriwether makes the journey so much fun the conventional final destination shouldn't take away from your enjoyment of the film. Meriwether has a snappy sense of humour that is extremely distinct, but what really makes her comedy so effective is it truly is relatable. I mean, if you can't laugh at yourself, who can you laugh at? But Meriwether, working with director Ivan Reitman (My Super Ex-Girlfriend), also knows when to dial up the absurdity and raunchiness, and these are usually the moments when No Strings Attached hits its high notes. (E.g., Emma's period mix and the scene where Adam first propositions Emma at a campground dance.)

Yes, it's important for a comedy to have a sidesplitting script to accomplish its ultimate goal, but it also needs a vast array of hilarious secondary characters and witty actors playing those parts, and that is something No Strings Attached has no shortage of. Kutcher and Portman might headline the movie, but the supporting performances are what really give the humour its pulse, especially the ones provided by Kevin Kline, Greta Gerwig, Lake Bell, Mindy Kaling and Jake M. Johnson.

Still, even though No Strings Attached pulls in a voluminous amount of laughs, there are times when you can tell, at least comically, that this is Meriwether's first experience as a screenwriter. It doesn't happen too often, but the movie includes some sequences where Meriwether doesn't trust that the audience will understand her jokes and jabs at pop culture. When a character brings up The Peach Pit in a conversation, we shouldn't have to be told it's a reference to 90210.

A few hiccups in material is somewhat excusable given Meriwether's career is wet behind the ears, but she makes up for that with the way she handles Adam and Emma's steamy fling. In many ways it's predictable, but at least she tries to shake up the traditional gender roles by having Adam be the emotional and needy partner. And while No Strings Attached definitely gets overly sappy as it reaches its conclusion (Adam's pivotal line in the third act is a doozy), Meriwether is still proficient at making her character's relationship feel genuine and honest, which is all that really matters in the end.

With her ability to mix the salt with the sweet, Meriwether really has the potential to become the female version of Judd Apatow. And, in my eyes, that's saying a whole lot.