I had seen most of the episodes because I was dating a woman at one time who watched the show religiously. Last night was date night with my GF and she asked to go see this movie.
We went, and afterwards I asked her if she liked it and she said it felt forced like they just made a movie because everyone wanted it and not because they had some great creative idea for extending the shows theme via a movie.
From my standpoint I only tolerated the show to begin with so I would never had seen this of my own free will. I thought it was just OK, kind of like the show. It wasn't very funny except in a few places and there was a lot about fashion which holds zero interest for me. The only good thing about it for me was the GF got bored too and that means she had more time for kissing and that is never a bad thing
All in all from a guys standpoint you can totally miss this movie and you really don't miss out on anything. From a girls standpoint if you were a huge fan of the show then wait for it to come out in video.
Also the movie is over two hours so if your GF makes you guys go, buy popcorn so you have something to do during the long sit
*WARNING if naked people bother you DO NOT go see this movie, there is a lot of both male and female folks with no clothes on doing some very graphic acts which do not omit various bits of the anatomy you usually don't see in box office movies. Quite a bit more explicit than any movie I have seen in a theater before, and that is all I have to say about that.