I just finished watching Blake's 7 : Series 1. It's 70s TV SF at its very best. Well, OK, maybe not its very best. It's quite good though.
The special effects have dated spectactularly, so much so, that it's quite amusing to watch some of the spaceship scenes. Brilliant styrofoam models. *chortle*. Actually, there are quite a lot of scenes where you can hear the actors sqeaking past the various styrofoam sets, especially in enclosed spaces. Now that's funny.
Having said that, the episodes are mostly engaging, not brilliant, but still quite watchable, and some of the chracters are a lot of fun. Avon, in particular is excellent. He's so droll, and always ready with excellent put downs. Have a look at some quotes. Avon features heavily.