I realize that this is an old thread, but I decided to look at the SciFi section, and imagine my surprise to find one of my favorite authors/series mentioned!
I love Odd! He's a great character. I think that the books started getting a little more (for lack of a better term) odd at Odd Hours. I felt it shifted a little more into the realm of unbelievability, if that even makes sense when talking about a guy who can see ghosts, etc.
That said, I also really like Koontz's Frankenstein series. It's a great read and you should pick it up!