This is an excellent book on Scheme, that covers R5RS thoroughly. The first part is a succint tutorial, most useful for those of us with no previous knowledge of functional programming: manipulation of lists, continuations, macros, etc. It is very clear, with plenty of solved examples and exercises. The second part is a thorough reference on every keyword and function of R5RS. There is nary a reference to particular implementations of Scheme, so it should be useful to everybody.
This is a dry book. I say this to its advantage. There are no extraneous comments nor attempts at being funny, yet the text is perfectly readable.
Typography is the truly standard TeX fare, and it looks very nice and 'functional'. Format is a bit wide, which helps the book to stay open where one leaves it open.
Many useful quasi-standard features outside R5RS (ie the SRFI's) are not covered. But for learning and practicing the language itself, I doubt there is a better choice. On the other hand, the full text of the book (and a handful of errata) is available online, should you not believe me (...)