When I started reading this, I figured I'd put it down pretty quickly due to the way it was written. As I kept reading it, the characters and the situations they found themselves in grabbed me. When I wasn't reading it, I was thinking about getting back to it to finish it.

Most all of the characters are pathetic, mean spirited and vile but something about this book makes you compelled to finish it.
The characters feel like real people and you are there with them for better or worse through all of their (mis)adventures.
Rarely do I find myself shocked by the contents of a book but Trainspotting made me stop more than a few times and say "wow!".