For prospective buyers who are still on the fence there's a handy 1000-word review comparing and contrasting The Good Parts with the Definitive Guide recommended above:
http://jmesnil.net/weblog/wp-content/uploads/2009/09/RzRcw.j...
http://jmesnil.net/weblog/wp-content/uploads/2009/09/RzRcw.j...