Definitely keep them in schools. Lonely glass cats are no good. They have to be put in a cycled tank, because they're sensitive to bad water quality. They can be hard to feed at first, but once settled they'll eat anything (I used newly hatched brine shrimp to get them to eat).
I think they are fantastic. I currently have a group of 9, and I'm planning on upgrading their tank and doubling the school in a few months.