It's a second edition, not a new book -- why did you feel deceived? There's a fair bit of restructuring of the first few chapters, and a whole new chapter on exploratory data analysis (which uses the new CSV support) and a bunch of new stuff about the new Unicode-character support.
Then certainly that my expectations were too high from what I'd read in the reviews, I was expecting a lot of changes like the second edition of the dragon book. You can see that some programs were obviously written to get around the memory limitations of the computers of the time, such as the assembler and emulator for an imaginary machine.
