csapp, really good?

[Mayuresh Kathe <mayuresh%sdf.org@localhost>]

i stumbled upon "computer systems: a programmer's perspective"
(url: csapp.cs.cmu.edu) and it looks like a really interesting
book for a newbie to systems programming under unix.
is it really good to warrant a purchase (expensive), or would
the book by "maurice bach" be considered good enough, though
the style of "c" used in the book seems a bit strange.
thanks.