The foliage downgrade is the most disappointing thing for me. The saddest part is they have (or had) the assets at some point but decided to do away with them. A lot of the screenshots coming out have a film of vaseline (TXAA maybe? or perhaps just screencaps from YouTube) over them which makes the low quality grass look like a blurry mess.
I haven't been watching videos in order to avoid spoilers, but I'm guessing that grass and the such doesn't animate like it does in the trailers either.
The being said, this isn't the downgrade that Watch Dogs was, but it's not going to be nearly as impressive as the upgrade that GTA V was. I think it will look great and probably play well, but the main thing for me is the story which I'm sure is going to be fantastic. It's a shame that it was being marketed the way it was (and really, still is), but I think Warner Brothers Interactive Entertainment has more to do with that than CDProjekt Red, although I could be wrong.