As a counterpoint, when my wife and I saw Rogue One we were both impressed that they managed to find somebody that looks just like Tarkin from the original film. I had no idea he was CG until reading about it after the fact.
I also was impressed with Tarkin, but once I realized what was going on, I saw the flaws. That said, for casual fans, they may not even notice because it took the realization of "Hey this guys dead" to open my eyes to it.
That said, the CG Leia was poorly executed, which was a surprise considering how well Tarkin was done. She really looked like a video game character. I would have preferred showing her head covered by her scarf and only showing her hands, like her intro in Episode 4. Maybe the production was worried casual fans wouldn't know who it was if they didn't show the face and goofy side-buns?
The main problem I had with Tarkin was that the facial scanning was obviously done very late in life - the cheeks were extremly gaunt, and, well, corpse-like.
I was thinking the younger characters are probably harder to do because they can't hide the flaws anywhere. Leia was very creepy in Rogue One, but it didn't even occur to me that Peter Cushing had died 20 years ago until after I finished watching the movie. His recreation was very good.
Yes, I couldn't help but feel like they were very well rendered video game characters surrounded by live actors, and I had to force myself back into the movie. I still have no idea what happened in the first scene Tarkin appears in.
I think this is why my two teenagers noticed it immediately when he first appeared. They instantly recognized being in a cutscene. It took me an extra second to go through an internal "Wait, he's dead, right?" moment.
I didn't notice it either. I would also be willing to bet that the majority of people who say his recreation was poorly done only say so because of having prior knowledge about the actor being deceased.
I thought Tarkin looked a bit creepy (in a bad way; the scriptwriters captured his ghastly Lawful Evil personality beautifully, and the voice actor (Guy Henry, who I've never heard of) did a masterful job).
But Mons Mothra looked fine, and I didn't get to see enough enough of Leia to tell --- and the other CGI actors I didn't know were CGI and completely failed to notice.
So it's definitely getting better. This was no _Polar Express_.
For what it's worth, Mon Mothma was played by an actress cast for Revenge to play Mothma (who was only seen in deleted scenes from that), and ended up aging to nearly the look of Caroline Blakiston in Return.
I thought he looked amazing when still and I didn't realize right away what was going on. It was when he started moving his face and walking that it became obvious. There's still a long way to go in making human motion appear more natural. It's still too "smooth" when rendered.
