Yes I used the seats on the old stock and it wasn’t a great nights sleep but it was ok. Dark carriage. Nice cosy chair. Warm. Reclining. It was sleeping in a chair which is generally crap. But it was cheap and it was fine for the price.
My brother and I went up to Fort William on the sleeper in Feb last year. We got on at Crewe and had seats booked going North , so of course had to get off and wait for the carriages to appear at Edinburgh before heading up to Fort William. It was only around Rannoch that we worked out you could recline them, doh!
Return journey we had berths and thoroughly enjoyed the experience on the old stock, great watching the sunset on the WHL with your head out of the window (the conductor (??) was more than happy for us to pop our heads out and warned us where to watch out for branches) .We spent a good few hours in the lounge car - mainly because there wasn't any service on the chip and pin machine to pay for our drinks and it was nice and relaxed if a bit dated. Not sampled the new stock yet and probably wont for a while.