"On Lisp" is a good book but perhaps too advanced for an introduction, whereas his "ANSI Common Lisp"[0] is better suited to the purpose. Barski's "Land of Lisp" has also received positive feedback.[1]
I'd be interested to see what others consider a suitable general learning path for Lisp.
The usual starting book is 'Practical Common Lisp' by Peter Seibel. Some advanced stuff then in 'Common Lisp Recipes' by Edi Weitz. Some older advanced stuff with examples: Paradigms of Artificial Intelligence Programming, Cases Studies in Common Lisp (PAIP) by Peter Norvig.
I'd be interested to see what others consider a suitable general learning path for Lisp.
[0] http://www.paulgraham.com/acl.html
[1] http://shop.oreilly.com/product/9781593272814.do