Well, I went to see it at the weekend, and I have to disagree with mthaler.
It's a pastiche of the old 30s/40s sci-fi serials that they used to show on Saturday mornings on TV - you know, the kind where each episode ended with the hero falling off the edge of a cliff, and the next episode started with a what you didn't see our hero do kind of thing.
Sky Captain brought back the memories of these films - cheesy as they were!
I think it's a good film if you walk in through the door not expecting anything. If you're expecting high art, you'll be disappointed. If you're expecting a good time, you'll have one!
Just my tuppence worth
Rgds
AndyF