XC first class is generally poor. The voyagers are just dire trains full stop; half the seats in first class don't align properly with the windows, so you're sat next to a bit of plastic. As the trains are so short first class is usually very busy, and isn't a quiet zone. Catering is generally poor too - microwaved filth which I wouldn't touch with a bargepole.
The first class carriages on their HSTs are excellent though, nice, big comfortable seats, big train so less busy, better lighting than FGW. Not sure about the catering as only been on at the weekend where it's tea/coffee/biscuits only.