Your flight will be tolerable but the seats will basically be the same as short haul Y. Don't expect any extra comfort.

United and Lufthansa are comparable IMHO. Lufthansa has a better reputation but their catering doesn't impress me. Onboard comfort will be the same unless you are on a United 10-abreast 777 which should be avoided at all costs (aisles are too narrow).

Pop a sleeping aid and the flight will go by faster.