Some reviewers seem to think this movie was not sufficiently faithful the book. Personally, I could care less. (And I'll happily say the same about film versions of books that are near and dear to my heart.) You want the book, go ahead and read the book. THIS City of Ember happens to be a movie. A really entertaining movie, that works amazingly well on its own terms. (And made me want to read the book, which you'd have to agree is a good thing.)
Other reviewers seem to think this movie ripped off the game Fallout, or the movie Dark City. Well, I'm afraid you are WAY out of touch with culture. This movie 'rips off' endless previous works. The first one I thought of was Arthur C Clarke's haunting novel Against the Fall of Night. Then I thought of the game Bioshock. Then Robert Heinlein's novel Orphans of the Sky. Then George Lucas' film THX-1138. Then a rather under-appreciated book by British SF writer James White, The Watch Below. And THEN I thought of Dark City...
None of those parallels bothered me at all. Why should they? I can't recall anyone disliking Bioshock as a "rip off" of Against the Fall of Night. The theme of people trying to escape from a 'lost' city is classic, well worth revisiting periodically.
And this movie does it really well, bringing a number of unique strengths. I very much liked the two kids that are the heroes of this story. I liked all the small characters, especially Martin Landau as the over-the-hill maintenance man. I LOVED Bill Murray as the villainous mayor. He should play bad guys more often. And above all, I really enjoyed the visualization of a 200-year-old city where all the technology has been failing for generations.
No, the story held no surprises. So what? Tell me you didn't know from the start how Die Hard was going to come out. Or Raiders of the Lost Ark. Or The Guns of Navarone. Or, in fact, ANY 'genre' movie. When the destination is known, it's the journey that's important. And I really enjoyed every minute of this journey, from start to finish.
City of Ember (the movie) is well-written, well-acted and visually beautiful. It's got a rousing story, quite a few laughs and a really great (if well-worn) premise. That's more than enough for me.