I think if you were going to boil down everything I've been trying to say about literature since starting this site, you'd end up with this:
If you look at the bestselling novels at any given time, one thing almost all of them have in common is that they could be described as fun. Obviously, fun is something we value in our literature. And yet in the common way we think about literature, especially in universities and "highbrow" book reviews, fun is pretty low on the list of things we say makes a book good. Which seems like an obvious disconnect between what we actually think is important in literature and what we say we think is important in literature. Granted that 'fun' can be nebulous and subjective, but so can most values we look for in literature.
So among whatever other criteria I use, for a book to be 'good' to me, it should be fun.