I was really pleasantly surprised at this book! I thought I would find it a bit slow even if it was good, but that turned out to be completely wrong!
It flowed very easily and despite the sometimes confusing scenario of dual universes (especially as we're dropped right into the story), it worked really well and the book managed to explain what was going on without huge info dumps.
I really liked Felix and while in the beginning his need to find out about his alter seems a bit odd (I guess because we never tried having a duplicate somewhere!), the book manages to also slowly getme to understand how difficult it must be to live in such a world.
The storyline is really well thought out and exciting and kept me reading! I won't reveal too much as that would be a shame :)
Definitely recommend it!