Peter Cushing was awesome
Indeed, not too shabby for a dead guy!
Seriously though, naturally I 'knew' just who that was with the first shot of him standing with back towards camera, and was wondering right away what they planned to do. Just leave the back facing and move on with the left rest to the imagination, put a somewhat similar actor in the role, didn't guess that they would completely CGI a person into the movie. Looked pretty darn good, even though it was still easy to tell it was CGI, I'd certainly call that a success.
Overall, thought the movie was great. Probably put it just after ESB in my overall Star Wars rankings. Which for myself, I now think stand at:
5, Rogue One, 4, 6, 7, 3, 1, 2