I actually found the Tarkin CGI convincing after the first scene with him, but I found Leia’s CGI very distracting and unnatural.
this was my opinion as well when just watching rogue one. but when i decided to pop in Star Wars immediately after, my reaction upon seeing princess Leia in her first scene was “Huh, i guess she does look like that”.
I think the thing that takes everyone out of the movie, is seeing a ‘new’ movie, but with time-traveling actors. We tend to think of them as we most recently saw them, especially when we know the movie was just filmed.