Re: Immortality is no doubt one factor.
To me it's worth it but I am so addicted to SF almost anything is "worth it".
A comparison is probably better, I would rate it ahead of the syfy channel Monday nighters, but a very close call with Eureka. I find it more interesting than the second half of this years Dr Who. It has been a big disappointment.
BTW, I have been commenting on the much bigger budget Starz mini-series, Torchwood - Miracle Day. It could be a bit of a wait for you, with no instant premium access. But what the hey, the way things work these days it might be available next month.