It's funny about pre-screening expectations. I had to be forced to see "No Strings Attached" because, 1, it stars Ashton Kutcher and, 2, because it stars Ashton Kutcher.

Did I mention that it stars Ashton Kutcher?

Surprise, surprise, "No Strings Attached" is an entertaining, enjoyable exercise in contemporary romantic comedy. I mean, you can do this kind of comedy only so many ways, but director Ivan Reitman (Ghostbusters") -- working from a script by a couple of writers -- finds a workable forumla.

The key? Chemistry. Not just between the surprisingly good Kutcher and costar Natalie Portman, which is strong enough. But chemistry among the whole cast, composed both of familiar faces (Kevin Kline, Olivia Thirlby) and a bunch of newcomers who fit well into the whole mix.

And the film, which has the woman character the one with the commitment phobia, has the perfect ending. No hearts and flowers, no wedding bells -- not, at least, for the principals -- no guarantees. Just simply the prospect of happiness.

What more would you want? More important, what more would you need?

And don't say Ashton Kutcher.

Below: The trailer for "No Strings Attached."