It is a lot better in the second half.

Well, yes and no. The story gets much more interesting, and his exposition on The Good is fascinating, but his metaphysical claims of Quality being a fundamental existing thing were somewhat weak.

I also disliked it and got 3/4 of the way through - I found it very pretentious and not nearly as full of wisdom as the author would like to believe.

Treat it as "unreliable narrator". I enjoyed it as a story, without taking too seriously any of the opinions which are put into the mouth of the main character (or... either of the main characters, if you prefer).

I'd put it on the "To Read When You're Eighteen, So You Can Reread It When You're Twenty-Five And See How Much You've Changed" list. Along with most of Ayn Rand and Nietzsche.

I recon that Sophie's World is much better than Zen

I learned most of what I know about philosophy from "The Bluffer's Guide To Philosophy" when I was about twelve.

It enabled me to win arguments with philosophy undergrads at least up 'til second year uni.