I'm going to assume that we all know by now that this is a film that eventually finishes with a fairly typical rom-com ending. But come on, if you seriously think that it shouldn't end this way, ask yourself how you would rather it ended. It is the journey that this film takes getting there that makes this such an enjoyable flick.
The premise is simple - Dylan (Justin Timberlake) and Jamie (Mila Kunis) decide that adding sex to their relationship is a great idea because its just physical. Eventually, they decide mutually to stop but remain friends and as the film progresses further we get to know them, and their families, and all their problems.
The fact is that there are not many movies I have enjoyed more than this, and this romcom just felt streets ahead of many others I have watched - the acting is good and it was something that a lot of romcoms aren't - it was very funny. Timberlake held his own with Kunis, and the supporting cast of Woody Harrelson (Tommy, the gay GQ sports editor), Patricia Clarkson (Lorna, Jamie's mum) and Richard Jenkins, who plays Dylan's father, provided some really good scenes (my favourite being the scenes between Dylan and his dad).
The sex scenes were well written, well acted, and well directed, managing to be fairly raunchy without going over the top. The dialogue was also really well written, and it was fun to watch Kunis and Timberlake play off eachother throughout the movie. Highly recommended.