Let's talk about amusement parks.
Parks have lots of different rides, some exciting, some for kids, some for families that everyone can enjoy. In this latter category you undoubtedly once sat through a ride that calmly ferries you through a wondrous world filled with animatronics and colorful scenes set to a certain theme. Nice to look at once, but not terribly exciting unless you are six years old.
The Goblin Emperor is such a ride.
It moves along at a fixed speed with only the occasional minor bump to make sure everyone is still awake. The reader doesn't have to do anything, but just coast along not unlike the book's protagonist. The writing easily supports this, which makes the final result even more of a shame.
Unfortunately, don't expect anything of note to happen. Even when something 'exciting' happens plot-wise, it tapers of immediately as to not jostle the reader too much. It was enough to prevent me from getting bored, but it never managed to excite either, which, now that I think about it, makes this one of the worst sort of books.
I suppose this makes a good book if you just want to veg out and not think about anything complicated. That's not what I read books for, however, but it might be for you.