I didn't find GEB helpful. It presented its information in a way that, if you're being charitable, sounded like, "Check out this cool thing these interesting people have in common that will tweak your brain!" The problem for me was that it often lapsed into, "Check out how cool I am that I can understand these acknowledged deep thinkers, and impose this pattern on their thought even when it's only peripherally appropriate!". Some of that perception may have been from my assessment of the people I knew who talked about it too much, though, now that I think of it.