The plot to Angel Beats revolves around Otanashi, an amnesiac who has been sent to the afterlife. Upon entering, he meets a girl named Yuri, who is aiming a sniper rifle at a white-haired girl. He stops her from doing this and warns the girl about Yuri, discovering her name to be Tenshi. She is vey grateful for Otanshi's warning, showing her gratitude by stabbing him in the heart with a knife that magically appears on her arms. Fortunately for Otanshi, he is soon to realize that dying in the afterlife is impossible, as he regains conciousness in a school located in the afterlife. Upon searching the premise, he is promptly attacked by a crazy guy with a sword and sets off a trap in front of the principal's office which promptly causes him to lose conciouness again. He awakens to find himself at the homebase of the Shinda Sekai Seven (also known as SSS), a group who's leaders, Yuri, has a strong resemeblance to Haruhi Suzimiya and has the primary goal of taking over the afterlife by rebelling against god. After being asked to enlist, he is unwilling at first, but after being confronted with the idea of being ressurected as a barnacle, he agrees. The rest of the show chronicles the ongoing war between the SSS and god's servant, Tenshi.
A few cliches aside (amnesia and Haruhi-clone), Angel Beats is an extremely refreshing experience, as it offers a unique story, interesting characters and exceptional writing. Dialogue between characters is very humorous and fast paced, making it a very enjoyable experience. The animation and art are superb, as the anime includes fast-paced and energetic gunfights and appealing character models. Backgrounds also look nice, as they are very colorful.
The opening is also something worth mentioning, as the song does a great job of fitting with the mood of the show. It starts off with possibly the most epic piano playing scene I have ever seen in my life, mostly due to this scene being beautifully animated. The logo then appears and the characters and their names are shown, first the two main characters, then showing the other members of the SSS. The opening does alot to remind me of Clannad, as I believe the same people who were responsible for the Clannad After Story opening, were also responsible for this.
Angel Beats is a show that holds much promise, as the first two episodes really show how great this series is. I have much confidence that this series will be the best of the Spring season, as the overall quality has yet to be matched by anything else coming out this season. Angel Beats is definitely worth a watch.