OK, I'm game. But first, if you have not yet finished the book, this is going to contain MAJOR SPOILERS, so proceed at your own risk.
As I first started reading the book, I was going along fine until the point at which Henry first met himself. I can't quite wrap my mind around one person being in two places at the same time. But then, I figured out that there could possibly be two, the chronologically aged Henry traveling either forward or back and either a future or past Henry. This works out until the fateful hunting accident. Future 43-year-old Henry travels back and since he has no feet is thrashing around and mistaken for an animal and either Clare's father or her brother shoots him, and before they find him, he time travels back to the present to die. But back in 1986, Clare sees Henry STANDING near her father and brother and signaling her to keep quiet. How can this be if he has lost his feet?
I thought for a minute that maybe a pre-frostbite 43-year-old Henry time traveled back to 1986 just after the slightly older amputee Henry was shot and disappeared, and that could have worked except that he clearly heard the other Henry cry out "Clare, Clare!" so it appears to me that at that point there are three Henrys, two aged 43 and somewhere else, the chronological Henry, who is 21 at this time, and has not yet met Clare. (The reason that I say both Henrys have to be 43 is that the chapter heading states that Henry is 43, and not 43 and some other age, to be consistent with other chapter headings.)
The other plot point that bothered me was Henry repeatedly telling Clare that nothing can be done to alter the future, yet he looked up and memorized winning lottery numbers and bought a ticket so that they could buy a house and Clare would have a bigger studio.
I have some other minor comments that I may or may not make as the discussion progresses, but I'll throw those out to start.
Sara