That's where I land as well: the new fx are great about 70 percent of the time. And that's good, because my DVD set is the TOS-R version. The quality of the
Enterprise varies a lot, because CBS switched to a better CGI model of the ship after the first few episodes they worked. That's why some shots in "Balance of Terror," an early effort, are not sufficiently photo-real:
http://tos.trekcore.com/hd/albums/1x14hd/balanceofterrorhd349.jpg
Some things, like Stratos in "The Cloud Minders," are a giant leap beyond what we had before. Some are almost as good as the original, like the space-going amoeba in "The Immunity Syndrome." And some are an unfortunate step down, like the Hangar Deck or the Klingon battle cruiser. But on balance, I enjoy the new fx.
I also like the original fx, often for their unmatched beauty and realism...
http://tos.trekcore.com/hd/albums/2x18hd/theimmunitysyndromehd0001.jpg
and sometimes more for their nostalgia value and geek historicity...
http://tos.trekcore.com/hd/albums/1x00hd/thecagehd0029.jpg