Be you ever return purchased books?

I'm in a bit of a quandary.

Last week, I finally got my hands on a book I've been salivating to read for over six months. I was really giddy to find it at the bookstore and stake a claim on my own copy. Then I went home and read, read, read until well-past midnight. 

When I finished the last page, however, I felt...kind of disappointed. Okay, I was really disappointed. The characters fell flat, the pacing seemed off, and the plot became predictable. All in all, not a terrible read but not a terribly good one either. 

So here's my little quandary. Should I return this book to the store? 

On one hand, I think this would be okay because I really didn't care for the novel and I'd be more than willing to exchange it for something else. Plus, I've taken good care of it---no creased edges or folded pages. It's like new. 

But on the other hand, I feel guilty about returning something I've actually read. I've already used the merchandise so wouldn't it be dishonest for me to return it? 

Decisions, decisions! Why is my life so hard?! Hahaha. 

So what do you guys think? Do you return books that you haven't enjoyed? I'm over-thinking this, aren't I?