I get Goedel's theorem, I'd like to think. I get strange loops, and how Hofstadter would have a field day with our criticism of xkcd and of xkcd's critics. I just know there's still more.
Is there more? Well, yes. I did just try to summarize the book in about 20 words.
Are you about 90% of the way through? Yes. The book is written in a style to make it have the trappings of more depth than it actually has. I actually enjoy it that way and do not mean it as a criticism. (I also enjoyed the Illuminatus! trilogy, which is self-consciously written with somewhat similar motives.) Don't undersell yourself.
It's a Dunning-Kruger trap, carefully laid in pretty prose to catch people like me. I'll never be confident that I've "finished" it. As a consequence, I'll always think Hofstadter is smarter than I am. There's evidence beyond the scope of GEB to support that, of course.
I happened upon the book in my life precisely when it would hold the least mystery, the second year of my graduate studies in computer science. It was fun but by that point in the category of "intellectual fluff" rather than "ow my brain". While I'm sure I have not discovered every last quirky little connection in it, every last pun or every last hidden pattern, I'm also pretty sure I didn't miss any of the main points.
But he's still smarter than me. I can read that book, I could never have written that book.
Are you about 90% of the way through? Yes. The book is written in a style to make it have the trappings of more depth than it actually has. I actually enjoy it that way and do not mean it as a criticism. (I also enjoyed the Illuminatus! trilogy, which is self-consciously written with somewhat similar motives.) Don't undersell yourself.