I back up everything that's been said about the new Caledonian Sleeper's seated coach. Uncomfortable and, in the small hours, cold. On the old stock I could get a reasonable amount of sleep, enough to function for a full day on arrival, albeit washed out by evening.
On the new stock, I rarely get any useful sleep due to a combination of comfort and temperature.
In addition the at seat catering fails yo deliver in a timely manner, with no option to go to the buffet yourself.
I'm now more likely to use flights or day trains if timings suit. It's still a good price, but is now a much less pleasant journey, to the extent that I suspect overnight coach may now be comparable. This would have been unthinkable on the old stock.