2 stars. I'm sure my rating would be much higher if anywhere on the book it said that this was the third book in a series. Since it doesn't, I can't give it any higher because there's a lot of stuff that didn't make much sense or have much of an impact because the events recall other books that I didn't read beforehand.
The book gave me a lot to think about. The author is a hell of a writer. I couldn't give it a full five stars, though, because of the structure of the book. A lot of times she'll make references to something and, instead of giving context, will just put a reference in the back of the book and a link to some website. This is fine if I'm reading a web page, but cumbersome if I'm reading a physical book.
Great story.
The only reason it gets four stars is that there was this huge plot point from the second book that gets completely ignored (save for a couple of sentences near the end). I kept wondering how the third book's plot would pertain to that event and when it didn't I felt a little disappointed.
If I had gone into this book without any expectations that it would resolve anything from the second book, I would have given it the full five stars.
The low rating I give this book is not the author's fault. The story that Stevenson penned is a standard in 19th century science fiction and as good if not better than anything Verne or Wells wrote. At least, that's the way I probably would have felt had it not been spoiled for me. Everyone knows the relationship between Jekyll and Hyde so when the twist was revealed, it was very anticlimactic. I would love to get the perspective of somebody who didn't know the twist; sadly, it's such a part of common knowledge that I don't think I'll see that.
Probably my least favorite of Neil Gaiman's works. That being said, the worst of Neil Gaiman is still better than 90% of fiction out there. If I had to compare it to anything, I would say it's very similar to Coraline. It's from a child's perspective and deals with his coming of age in the midst of supernatural events. I much prefer the Graveyard Book.
I've only read one other “kid's” book by Neil Gaiman and that was “The Graveyard Book.” I always thought that the only reason that book was classified as for children was because it had a child protagonist. The story was deep and could be enjoyed by adults. Interworld, on the other hand, was not. Not a bad book, just clearly meant for children and reminiscent of the Animorphs and Goosebumps books I would read as a kid. Don't expect any nuance.