Let me start out by saying, these are really nice. The quality is very high. I think they are both close enough and still different enough to the originals to just about make everyone happy. Some of the more noticeable differences, as has been mentioned before, the Starchild no longer has the Captain's molded hair and the Catman doesn't have Lex's molded eyebows.
For comparison pics of vintage vs new be sure to check out Rche's great thread:
12 KISS comparison Mego vs CTVT pic heavy!! - Mego Talk
There are a few tiny things I would have liked closer to vintage. Like, the Demon's chains don't hang the same and the openings on the side of his tights on his legs are too small and Pauls belt fits too loose. But other than that, I really don't have any complaints on the outfits.
The new bodies are great and don't have any of the twisting issues the 8 inch ones have. If you are only going to get one set, I'd recommend getting the 12 inch figures.
It's kind of hard to describe my feelings on seeing these in person. To me, they are the most Mego of all the re-Megos to date. They seem the most Mego. If that makes any sense at all. It's almost like, back in the day, Mego had made another run of them a couple of years after the originals. They are the same but then not quite. Kind of like how Mego slightly changed and updated the WGSH figures over the years or all the bazillion variations on the materials used on the Dukes. Am I making any sense? Eh, probably not.
Anyhoo...here's the pic.