An interesting and enjoyable series. I found the various phenomena inflicted on our characters to be interesting ideas which raised a lot of "what if" questions for if you yourself were facing a similar situation. I didn't think the concept was always executed as well as it could have been, but it was interesting nonetheless.
I generally liked the characters, although at points some did annoy me a bit, Iori being the main offender (especially in the final arc). The series did tend to get a bit too angsty for my liking at times as well, but not to a degree where it ruined things too much or stopped me watching. The final 4 episode arc, which was aired a couple of months after the "regular" TV broadcast ended, wrapped things up quite nicely and gave a satisfying conclusion for me, whilst still keeping the door open for a possible sequel.
Overall, a very enjoyable watch.