Many have reviewed this, so I won't spend too much time praising the particulars. Given my own interest in horror stories and the almost universal high reviews, this seemed like an obvious choice for a dark and stormy night after the kids were asleep. (It was a good choice.)
This one frustrated me in a few places, but the hints were excellently graded such that you had plenty of "nudges" to work it out for yourself before the game gave up on you and told you what you needed to do. I completely missed the chance to put the final pieces together, as far as what is going on, but on reflection (and a few replays from a well-timed save game) I can't blame the game for that at all; the clues were there, I simply didn't attach much significance to them. Paying attention to detail pays off.
Multiple solutions to the final conundrum. Make sure to read the appendix (sort of an afterword) after each ending before trying for a different one, since that changes with the endings, too. I haven't found everything yet, but I expect I will start over from scratch sooner rather than later so I can better appreciate the stuff I missed the first time.