Each to their own I guess.
I love the dialogue. Neither too clever clever nor of the 'tell the audience what is happening' type. It flows, doesn't clunk. I don't feel there's a word wasted. It builds characters so you have this idea of how they might think, feel and respond.
More than that though, I find there's something about the way the whole thing is put together. It has a suspense, and I feel that that's through your interest in character rather than though any plot device. Personally, I can't wait for the next episode. No real idea where it's going but that's part of it!
Btw, I thought Jacqueline Bisset was excellent - I didn't know it was her to begin with either.
Oddly, I'd say that if (for me) it has a weak point then it was the music. I find it very acceptable and authentic big band jazz but not special in any way. But, tbh, I wouldn't expect it to be so even that's not a criticism.