I jsut watched Sky Captain and the World of Tomorrow and while it may not be as good as say The League of Extraordinary Gentlemen, it was well worth the download.
On Kushan's scale of goodness, It rates as a 3.
If you are unfamilliar with this scale, it goes like this:

0 - Pretend it doesn't exist
1 - Download it
2 - Watch it if it's on TV
3 - Rent it
4 - Go see it in the Cinema
5 - Download it to see it as soon as possible, then go to the Cinema and give them money because you downloaded it and spend all your money on products endorsing this fine movie..

An example of a film rated 5 would be Shrek 2.
An example of a film rated 0 would be any Sequel to the Matrix....if they ever make one that is.

2