What makes a good book?

I like a book I can get into. I like a book that I feel like I can imagine me being right there as the story unfolds. I want to feel like the story is imaginative but believable at the same time. If it is to far fetched I feel like it is to much of a story and I cant get into it.

I personally enjoy a good thriller or mystery.

I do not have to agree with the main character but I need to understand why he/she does what they do. Character development is so very important. Also things should be beliveable. If you are writing fantasy you should set up your world in a way that I could imagine what you are wanting me to imagine happening there. No matter how unrealistic in this world it may be if you set up the story right the reader will be able to belive and participate in your story line. Fiction is the same way, make what you write possible for the world you are writing in. I hope that this makes sense.