I thought Evolution was just middle of the line. It wasn't bad, yet it was far from great. As many of pointed out previously, the script/plot was WAY too much like Ghostbusters, except it wasn't nearly as funny. Orlando Jones was, believe it or not, too serious for my liking. The fat guys were stupidly unfunny. Chris Farley can never replaced by anybody, let alone by two people.
There were some high points in the movie, however, that might draw some of you in. Some of the FX were VERY impressive. There was one point where I really thought I was seeing a live action creature, when it actually was CGI. I thought Duchovney did some fun work, including -- yes -- the mooning scene. The shameless head and shoulders bit at the very end was great, too.
Go see Shrek before you see Evolution, but see Evolution before Tomb Raider, The Mummy Returns, or Pearl Harbor.