I saw the movie Friday night, and I've got to say, I went in thinking it would be horrible, but it actually wasn't a bad movie. For lack of a better word, though, it was kind of dumb. It was awesome, though, for the fact that Channing Tatum, Marlon Wayans, Sienna Miller, and Rachel Nichols showed up. Sienna and Rachel = effin' GORGEOUS in person. They look way different in person than they do on film.
It really struck me as a kids movie that was trying to hard to be an adult movie, and I think they should have pushed to take one angle or the other. However, the only absolutely awful thing about this movie was the CGI. It's the most outdated CGI I've ever seen in a movie (yeah, even worse than Wolverine's). Next to that, Channing Tatum's performance was terrible. Many times, he'd be yelling, with no expression on his face, and many of his lines that should have been emphasized were not, and vice versa.
That said, Marlon Wayans was funny as hell, and Snake Eyes was great, but they undercut him by a lot. I really wish he had more fighting.
So, all in all, not a bad movie, but I wouldn't call it great. It's a good action flick (GREAT action) that's cheesy, but that's kind of expected of a G.I. Joe film.