I wasn't a bit fan of the first G.I. Joe, having only seen bits and pieces but I really liked the cartoon, my fave two being Snake Eyes and Storm Shadow. Both were main characters in this movie. (And might I add that Storm was portrayed by one of my favorite actors, Lee Byunghun?)
That being said, it was a pretty rollicking good movie with lots of explosions, a really awesomely strong female characters and The Rock, which is always a bonus.
Random note, I am not ashamed to admit I ship Snake Eyes and Storm Shadow. Hell, I think I did that when I was like eight! XD