Dissapointment!! Oooooh, the dissapointment! Nagisa coming back to life, whether it's an alternative dimention fo whatever... Well, it wasn't that bad but it could have been loads better. Like Okazaki helping Ushio to grow up into a great person, just bringing Ushio back to life is good enough. Nagisa too was just too to the extreme point.
What I did find amazing was the whole junk-being and the girl to just explode with the world and all and come back to their "other self". The whole explosion scene was intense.
One question though. Since Ushio's the girl in the world that ended, Nagisa, her too would naturally know about it(in CLANNAD, the theater play). However, the girl in the world that ended existed long before Ushio was ever born. Then if that were to be the case, it means she moved from Nagisa to Ushio since Nagisa died. But then, Nagisa came back to life in the ending. And so, the girl is Ushio. But then, the question becomes "how does Nagisa know about the world that ended, the girl and the junk-being-robot?"
...Did I make it sound too confusing?