It is about 2 girls, one a normal school girl in the real world, the other a girl named Black Rock Shooter in an alternative supernatural universe filled with constant fighting. The style of the show is where what goes on in one world is mirrored in the other world. The real world half could be considered a School, Drama, Slice of Life, Shoujo anime. While the Black Rock Shooter half could be considered an Action, Super Power, Shounen anime. In an interesting way, they kind of work together to be almost a translation of school age girl issues so that boys can understand. But this is only up to about episode 5 when the main plot kicks in.
The story is good, the art is a little disappointing if you compare it to the OVA. Characters are decent and it is a good anime to watch overall.
For those that have seen the OVA, this is a retelling of the story. Basically they didn't like the first one and expanded it greatly adding more girls other than Black Rock Shooter and Dead Master. Where the TV series' BRS side is a reflection of what is going on in the real world, the OVA's BRS side was telling the story of BRS trying to save Dead Master after the events of the real world side.
For those that are reading the Manga, they are totally separate stories, involving the same characters but the premise of the universe different to the point as the stories are mutually exclusive.
I, personally, love the switching back and forth style of storytelling, so was quite happy with it. Some people, I know, do not like this style as it melts their brains which can't handle jumping back and forth between stories. Whether you like it or not probably depends on which side of the fence you are on, but overall it is worth watching if only for the really cool fighting sequences in Black Rock Shooter's world.
