I can't remember why or when I wanted to watch Angel Beats! but I do remember enjoying it quite a bit. If I wanted to watch it, it would probably have been for the animation, as this is a treat for the eyes; it has to be one if not the best anime I've ever seen visual-wise. Everything looks so... polished and different from the usual stuff, like a tiger among cats; sure the cats look good, but that tiger is in a class of it's own who will tear those other cats apart. So, so gorgeous.
The sound is great all-around but I must mention the beautiful OP. I love how the piano doesn't stop, how it can still be heard even when everything else is playing and how the OP doesn't switch to rock or anything heavy that would disturb the piano or the mood it sets. The other instruments and vocal enhance the majesty of it and make it into something wonderful. And the other version is pretty good, not as good as the piano one though. The VO work, especially TK but otherwise, don't have much to say about it. But damn, love it when Angel activates one of her moves through voice command.
The worst thing I can say about this is that I wish there were more backstories to the characters, as only about half have them explained. And it wouldn't do to say who did or didn't get a backstory but I must mention TK; the english speaking (Kinda), bandana wearing dancer. We know nothing about him apart from that he's cool and that nobody knows anything about him (Contradiction? Probably...). It is a shame... but the characters overall were pretty great, each having their quirks, their traits, what makes them different from each other; how they're themselves and no other. Just wanted more to their backstories, more development.
The story was good, pretty good but not excellent. You got the synopsis and the fact that they're essentially immortal; dying is simply a timeout that lasts a short time (You'll learn this early on). But death in this world (To vanish), like death in our world is something completely different than a timeout. It's hard to explain it without giving away too much, but it leads to one of the best aspects of the show, so I'm not going to try. At some parts, I just wanted more. It should have gone on longer than 13 episodes, as the last few episodes seemed... cut up, or not entirely together. Kinda broken up and missing a few components. Coupled with the already mentioned character development stuff, it brings it down. What's there is pretty good, but it's not enough.
A quick note before I wrap this up: what can top the comedy and maybe even TK's coolness is the sad moments, or tragic moments. Some real tearjerkers here.
If it was longer and with more backstories given, especially TK's (I'm repeating this a lot but the backstories are one of the best parts of the anime) then it would be on the top of my list. But what's done is still quite good, and I'll definitely remember it for quite a while.