The special effects were much better than average, and if I had known going in that it's almost an homage to the 40's era comic-book-style movie, I might have enjoyed it much more. The characters are entirely two-dimensional (even Law's former love interest with Jolie falls flat), and entirely predictable. The plot leaves nothing to the imagination - by the time we find out a mad genius wants to destroy the world, we don't really care, and are not entirely surprised. All the exposition is force-fed in tiny chunks to the audience, and it's always too little too late - by the time we realize why it's And the World of Tomorrow, it doesn't even matter - the climax is already upon us.
The main problem with the story is that the protagonists are continuously willing to lay everything on the line for the wildest shot at something that can drive the plot. One scrap of paper held up with gum sparks a trek to the Himalayas. I almost wished they died slowly of radiation poisoning in the uranium mines - the plot would have moved about as fast.
The setting and the effects will probably be the only parts of Sky Captain worth remembering. There are some especially cheesy rendered sequences, but the better part of the movie is fun to watch. Not mind-blowing beautiful - just fun to watch. There is a perpetual gauzy filter, which throws you back to halcyon days that never were, and a time in the 1940's with giant robots and no Nazis. The film keeps its retro 40's throwback feel consistent, even if it can't decide what kind of gun Sky Captain is actually carrying.
This was my largest problem with the movie as a whole - consistent references to a timeline that is never fully explained. The movie opens with a shot of Hindenberg 3, and German dialogue. World War I is constantly used as the starting point for the history of the main villain. gnfnrf and I place the movie's actual real-world time to roughly 1940-1947 - and there are no Nazis. No explanation as to why there are no Nazis, no explanation as to the victor of WWI, no explanation as to why every military person on Earth dresses like a Nazi. If Germany won, I'm okay with that - but keep mentioning how President Roosevelt is doing in office, and we're going to keep wondering how WWII's going along.