G.I. Joe is the latest offering in a series of action-figures based blockbusters: after Transformers and Transformers 2, and before Lego, it brings to life the much-loved (?) Hasbro characters.
And yes, this film has in common with its predecessors that the plot is fairly light, fanboyish and leads to a lot of grand scale explosions in well-known landmarks. But despite being quite simplistic, G.I. Joe's plot is at least well constructed: despite wide-open plot holes such as the existence of a massive particle accelerator in the centre of Paris, there is a calculated progression and the targets are always clear (secure, prevent, retrieve, save the world in that order).
Yet, despite a sterling perdormance on Tatum's part (along with quite under-average acting on the part of the rest of the cast, yes, even Chris Eccleston), the film fails to make the viewer care for any characters. The frequent use of flashbacks should help, and, clearly, they were included for that purpose, but they were used in such a cliched way that they simply don't work.
So the highlight of the film is its light-heartedness (look out for great names, and a great firing command) and its explosions. In Paris. Just to see the French capital getting its back kicked, should be enough reason to watch G.I. Joe. I mean - seriously - look at the trailer!

Admittedly, Team America was there before, but that was meant to be funny. Ho-hum. And the effects weren't quite as good. So at the end of the day, I'd recommend watching it - with brains switched off.