Should I upgrade to Leopard?

Simple enough question. Tiger’s doing just fine for me right now, but I’m hearing great things about Leopard. Here’s what I’ve got:

15” PowerBook G4
1.67 GHz PowerPC G4 Chip
1 Gig of RAM
80 Gig HD, mostly empty

I do have a big LaCie drive, so I would get functionality out of Time Machine. Also will be getting an iPhone for Xmas, if that matters. And Spaces sounds amazing.

I just want to be sure that the OS isn’t so big that it’ll overpower my chip and RAM. Anybody having a good (or horrible) experience with Leopard on a machine with capabilities similar to (or lesser than) mine?

Thanks!