Angel Beats was produced by the same studio that did Clannad, Lucky Star, Haruhi and many of anime shows many people regard as being excellent and in general are well loved by the fans.
The anime starts off with Otonashi appearing on the school grounds confused, without any memory of where and how he got there, upon encountering a girl called Yuri who has a gun aimed at 'Angel' he immediately jumps into action not realising he is infact dead, and in limbo per say.
Quickly trying to grasp the situation he has found himself in, he joins the 'Afterlife Battlefront' a group of students who are fighting against God and 'Angel'.
In some ways this anime is more slice of life, but it is also very tragic. Each and every character in this series has a story to tell about how they died, and why they are there. Each character has issues to resolve and this is how this anime really comes into play.
The school inwhich this anime is based at is populated by what they describe as NPCs, students created to populate the school but don't possess a soul or anything.
One thing you will notice about this series is the animation, it is quite frankly amazing.
Although this anime has a lot of action and comedy moments, there is also a 'rock' band called Girls Dead Monster, who perform a wide range of catchy tunes that are really good.
The English and Japanese languge tracks are quite good.
I clearly regard this as one of the best anime shows ever made. It's so good, yet so sad.