It was pretty good. One of my biggest worries about the movie (aside from being a video game based movie) was Jake Gyllenhaal, he is a good actor but he really didnt seem to me like the actor I would choose for the role of the prince and I still think he might not have been the best choice but after the first 15 minutes I got used to him and he actually played the role of the happy go lucky prince from the Sands of Time very well. The dialog was better than I had expected from such a big summer blckbuster and even the story wast half bad. The actions scenes where mostly very good but the movie did suffer from the "10 minutes has passed since we last killed / ran away from something which means its time for a new action scene" problem but it wasnt so bad because lets face it you dont go to see this movie for its deep and poetic dialogs.
Basicly if you want to see a fun stupid movie with high production values and great CGI go see it, its about as sophiticated and fun as the first Pirates of the Caribbeean was. 
 
The only big problem I had with this film was that I left the theater with one big question unanswered, will the movie mark the triumphant return  of TANG?