I thought the point of the speech is to be a roast, and in that Colbert did pretty well. He wasn't nice to the press either, but Bush appeared to be a good sport.
I don't know about the "good sport" stuff. Granted, he wasn't petulant like Clinton during Imus, but he did not look amused.
Even though I thought he was funny, when MSNBC put up the splitscreen with W. in the corner, I couldn't stop cringing.