Where to begin; after reading this thread I have come to the conclusion that most of the people who had watched this and Clannad hadn't been around for AIR or the like. Reincarnation is a HUGE part of the Key franchise, and after watching this I can safely say that it is indeed a Key show!
Spoiler for 13:
So this is the end huh? Well it felt right to be honest, following the writer's trend it ended in a way that felt good to me as a fan. It did exactly what was promised and nothing more. The subtle hints that Otanashi was in love with Kanaede was well placed throughout the whole series; he was after all just following his heart.
As for how the character's changed in this episode, think about this; how do YOU act when alone and how do you act with others? It's all about Proxemics.
It had a pretty good couple of twists some expected others less so. And yes it WAS a little rushed, but that was why it's a guinea pig mix-media project. It felt ackward because we aren't seeing all of it, due to mixed media, and the reason they will struggle with it is this very reason. I forsee a few OVA's maybe a second season to show what happend in the "mixed-media" that no one will ever see.
It had some good philosophical ideas, that I'm sure will be missed by those with closed minds. Some great moments, and a few characters that will likely pop up again in the future for Key.(EVERYONE LOVES TK)
I have to ask myself did Otanashi come there by accident? His memories may have been wiped, it seemed as though more by design than anything else. The NPCs were all coming back and the world was resetting preparing for the next wave of incoming souls. I don't forsee him sticking around without the SS. I have to wonder as well if this was a place for children who had unfinished ends... what the hell was up with the guild with it's 30+ adult members!?! If they have been there for as long as I assume, knowing that people in that world DO age, then they saw the last incarnation of the last class as well. Working so close to the second computer lab for so long, there is no way they didn't know it was there.
Overall I would rate this a 9.4/10 (couple points off for being rushed and couple of extra points for attempting to pull this crazy wild mixed-media stunt!)