Never seen Sapphire & Steel before, but my better half raved about it from when she was a wee bit younger.
A definite 60'/70's feel to it, but well written, and, very welcomed in this modern age, not at all rushed. Plenty of time is given to tell the story, and characters actually have time to develope subtly, rather than in your face development of both plot and character.
The concept and stories are interesting, meandering to their conclusions, with enough surprises along the way. Mysterious and unexplained.
Don't expect to get everything (or indeed anything) explained for you. These need a bit of brain. Nothing is spoon fed, and if you can't both think and use your imagination, you will be left thinking 'what just happened?'
Gets the thumbs up from me......