Let me start off by saying that i truly loved this anime, but it was just way too rushed and the one thing that suffered the most due to it only being a 13 episode anime, was the romantical element. Angel Beats! had so much potentiol in it's characters and plot to include a little bit of romance. I felt no real bond between Otonashi and Tenshi till the last episode in the last scene. Until I saw Yuri disapear I literaly though that Otonashi was going to go for Yuri. That was honestly how missleading and vague the romance for Angel Beats! was.
Another badly planned out part of Angel Beats! was the overlapping time. How was Tenshi in the afterlife before Otonashi if she got his heart after he died?
Asside from the flaws this was a very lovable anime, from the characters, to the plot, and the animation it was all great. One of my favorite things about this anime was the story telling of the characters and what happened to them when they were "alive". It really created a great mood. I don't think i could have wished for anything better.
If it wasn't for those two flaws (mainly the rushing of the romance, i didn't mind the timelaps) Angel Beats! would be an easy 10/10 for me. It would have surpassed clannad in my opinion.