Yes, comfy and conducive to a good sleep, though I can't say that I ever remained asleep after landing till being interrupted by Movements staff clambering up the stairs outside, as a colleague once claimed. And I recall being advised that, to get the best out of them, one should get properly undressed, no lying there in flying overalls!
In practice, however, I don't recall them being used too often. My impression was that they had been installed against an expectation of lots of double-crew operation, something that didn't happen.