I'm a finisher. But I tend to do my diligence before I start, so even if I am not particularly thrilled about the book at the end, I find there is usually something to glean from it. A few nice passages in the context of a book I'm otherwise not enjoying much is a nice experience, I find. Plus, reading other styles of writing in general is good for comprehension, I think. The more you read, the more of what you read starts making sense.