That's pretty much exactly how I felt about Divergent - I flew through reading it and I enjoyed the story, but after finishing it, I wasn't that impressed. I think this series is going to be next on my YA lit list - since I'm going to be a children's/YA librarian, I want to be familiar with the "in" series, even if they're not the most sophisticated works of literature out there. I guess the good news is that this series sounds at least enjoyable, even if it's flawed - at least, based on your review :)