[hudibras]

I agree with everything here, including the praise for Matloff's book; it should be the very first book any serious R user picks up.

But Matloff is no longer alone: Hadley Wickham's Advanced R is now also a must-read for R programmers.

http://www.amazon.com/Advanced-Chapman-Hall-CRC-Series/dp/14...

[hadley → hudibras]

And Advanced R is also available for free at http://adv-r.had.co.nz/