I enjoyed it back in the 70s. Decided to have a go at watching it again, although I was afraid it might be too dated. Turns out, yes, it is a bit dated, and the acting from some of the lesser characters is pretty ropey (especially the children), but the main actors are brilliant. After a slow couple of episodes at the start, I've been enjoying the rest very much. I'd forgotten how comedic it is. My memory was of it being more serious and worthy.
By the way, I'd also forgotten that Jean Luc Picard was in it.