There is nothing I can say here that hasn't been said before.....but I think I should say it anyway.
The idea for this book is amazing; it's an idea that makes you wonder why no one wrote it years ago. Every reader would love the chance to meet their favorite characters in person, wouldn't they?
Mo was somewhat useless in this book, but he gets better and better as the series goes on. By the end of Inkdeath, I like him as much as anybody. Dustfinger was odd to me at first; I couldn't decide what I thought about him, but halfway through Inkheart, it occurred to me that I wished he was around more. That struck me as a good sign. Meggie .....is okay. I don't hate her. I didn't care for Elinor at all, but thankfully she was mostly written out of the other books.
My only real problem with this book is the repetitive factor. After they escape the first time, the book seems like it should be winding down, but then they get captured again and put back in the same place, for the same reason, again. And then they need to escape again.
A few of the characters are superficial, and some of the dialogue is so blunt and obvious it was clearly intended for very young children, but overall, this is a very good book. And in my opinion Inkspell is twice as good, and Inkdeath even better. I think it's worth reading this one just to get to the others.