Very very comfortable. I've never spent much time in the pilots' seats (P1 & 2), but many hours in the jumpseats and these are VERY comfortable. Nothing like a normal airline seat. For a start the thing is really designed to support you and keep you alert for up to eight hours or whatever, plus you have the extra shoulder straps for take off and landing, which means you don't have to use any physical energy to stay put during deceleration on rollout or neg Gs at the top of a descent. You don't budge an inch in turbulence. You really have a sense of "strapping the aircraft on". Oh, and the view - for those of you whose travel requirements restrict them to N-reg metal - is FAB.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz