There seemed to be a lot of emphasis placed upon the "magic" the coin held and whether or not it landed on heads or tails which I found somewhat confusing. Later on we find out the true significance of the coin's "powers" which left me feeling super dumb. LOL! Why? because there's a whole lotta sciencey stuff that goes into it that uses big words like, quantum shifts, Physics, analog and gyrocompass and my brain just wasn't built to process those. However, this concept of parallel universes and doppelgangers would be a no-brainer for my twelve year old science whiz. :)
There is a lot for the main character, Ephraim to consider because each time he "flips" into another universe, he's not just changing things for himself, he's affecting another "him" and everyone else around him. A lot happens, both good and bad, and he and his traveling companions have to consider that just because you can do something doesn't necessarily mean you should, nor does it make it right.