Looks like the critics agreed.
40% rating from Rotten Tomatoes
Consensus: While fans of the Hasbro toy franchise may revel in a bit of nostalgia, G.I. Joe: The Rise of Cobra is largely a cartoonish, over-the-top action fest propelled by silly writing, inconsistent visual effects, and merely passable performances.
C- for Yahoo movies:
Critics Reviews Average Grade: C-
Boston Globe, Ty Burr
"...a loud but proficient slab of explode-o-rama summer blockbuster nonsense, perfectly entertaining if you like that sort of thing, extremely skippable if you don’t." more... B-
Chicago Sun-Times, Roger Ebert
"There is never any clear sense in the action of where anything is in relation to anything else." more... D+
Chicago Tribune, Geoff Berkshire
"That G.I. Joe is completely ridiculous should come as a surprise to no one. That it's not an outright disaster might be a different story." more... B-
E! Online, Luke Y. Thompson
"...Frequently laugh-out-loud cheesy, and the digital effects are highly dubious." more... C+
I also said Roy Jones Jr and Anderson Silva were destined to fight.
Now for my next prediction. G.I. Joe will be out on dvd no later than October, and Anderson Silva will destroy Roy if they fight in the UFC, but Roy will not destroy, but retain a convincing win over Anderson Silva if they just box.