Fantastic book. The problems are interesting, and nicely bring out the connections between topics that would on the surface, seem to be disparate.

Cover and Thomas is more textbookish, and in some ways, more detailed. Personally, I'd read this first, and then take on the interesting topics in Cover and Thomas.

I read a lot of math books, and I'd put this right on top along with Needham's 'Visual Complex Analysis'.