I had the very good fortune to read Airborn by Kenneth Oppel while knowing next to nothing about the book. I'd seen the dirigible/airship thing on the cover, but that was about it. Every thrill was doubled because it was unexpected.
Even the opening pages are exciting, in part because you think you're reading about a kid in the crow's nest of a sailing ship and then realize that, of course, you're not.
I don't want to give too much away so that other readers can have the same experience I did. I'll just say that if Airborn isn't true alternative history, it at least involves an alternative world. Once you accept that alternative world, accepting everything else that's going on is no problem.
While reading the first third of the book, I felt that Matt, the main character, was a little on the flat and dull side. Something exciting would happen, and then we were back to dull, old Matt. But he became more dynamic and interesting as the story progressed.
And get a load of this website! (But stop after the introduction. If you read the newspaper, you'll be tipped off about things that are going to happen. Don't want to spoil any of the thrills.) I think it's the sound that grabbed me.