From The Movie Snob:

Sky Captain and the World of Tomorrow (B-). I was a mere lad when the Age of Special Effects was inaugurated by a little movie called Star Wars. (Excuse me, I mean Episode IV: A New Hope.) I can remember some movie reviewer’s embarrassing himself back in those days by considering whether a movie could succeed solely on the strength of its special effects and answering "yes" based on the seemingly contrary evidence of Disney’s Tron. At the risk of similarly embarrassing myself, I’ll cautiously venture that the FX actually do justify the existence of Sky Captain and the World of Tomorrow. As you may have read, this movie was shot entirely against blue screens, so that virtually everything, except the actors and a few foreground props, is entirely computer-generated. I thought the movie looked great, and there is a plot of sorts as intrepid pilot Joe Sullivan (Jude Law) and intrepid reporter Polly Perkins (Gwyneth Paltrow) team up to fight a mysterious villain who periodically unleashes unstoppable giant robots on the world’s major cities. The script, unfortunately, seems to have been computer-generated as well, so the movie’s charms are entirely visual. You’ve been warned.