EDIT: I quickly misread the question and referred mostly to the book, but the same things applied to the "culture" as well
Ok, biting the troll bate and here we go :)...
1. Lack of focus on "just making (cool) stuff" (compare it with "Dive Into Python" and other Python or Perl tutorials) - it didn't feel "hacker/maker spirit" at all
2. Too many words, too little code - I think in code, pictures and occasionally equations: words are ok too, but not when their only purpose is making "opinionated" jokes. And the illustrations literally hurt my brain - I expect nicely crafted images that explain concepts, not weird jokes that have nothing to do with them!
3. Not many interesting concepts - I'm ok with not focusing on making "coll stuff" with a piece of technology you're just learning and with not being "hacker spirited", but if you don't do it this way, at least present interesting mind-opening concepts to the reader (just compare it with "Practical Common Lisp" or a Haskell tutorial - they give you so much tasty mindfood that the style doesn't even matter anymore, they could've been written in the style of a medical research article and still be enjoyable to read). Ruby didn't bring any interesting new concepts to me - it was Smalltalky OOP and the coolness of blocks that could've been just lambdas anyway...
4. Lots of stupid jokes that I didn't find funny at all, and made me feel stupid that maybe there was something I didn't understand but was supposed to, and cultural references that were very "WTF" (I'm European, but I've been pretty well exposed to US culture and I like "american style humor" but this felt like totally from a different planet).
5. This one is subjective don't mean to offend, just to be honest: I hate the whole gay (not necessarily in a sexual way), touchy, feely, friendly way of presenting technical things - I'm more of a "cold British humor", occasional "mildly offensive jokes" and a touch of "mental testosterone" kind of guy (this is the king of attitude that, for example, appeals to me in an aesthetic way: http://programming-motherfucker.com/ )
6. Despite being clear that learning resources like WPGR were opinionated and would only appear to people whose minds work in a certain way, they were recommended to all newbies. I like a culture that doesn't shove opinionated stuff in the face of new guys - first let them find "their own way", then show them the "opinionated ways".
7. There was a "split personality" thing that annoyed me: Ruby as a language appealed to the "hacker spirited" a lot, but the community was pulling in different direction that I couldn't really comprehend - a weird lust for a code-aesthetic-nirvana or something...