I watched the originals when they were new in the 80's and I say, this new one looks fine art wise. To me Liono's hair isn't pink, it actually looks like there is blue added to the red which makes it more a purple than pink. Either way it looks fine to me.
The overall design looks more updated to today's animation style while still keeping most of the original design. Especially with the weapons. Cheetara also looks much more physically expressive in this art work. In the original it was Liono, Panthro, and Mummra that had physical expression; the others weren't so much expessive.
I think this is good as long as the stories are good. The first one had some decent ones. It seems in recent years depending on the audience the toon/anime is aimed at the stories can be very sophisticated and not insulting to intelligence (Avatar: The last Air Bender). I hope that is the case here. In the original the stories would tank when they focused on the twins or Snarf. Snarf was written in for comic refief, exposition, plot convenience, etc. Because of this he felt forced a lot and not an actual character. Simular with the twins. Mummra was also painfully one dimensional. They don't have make him hardcore fleshed out here, but at least give him a little more to do than to Pinky and the Brain the Thundercats. "What are we going to do this week Mummra?"..."Same thing we do every week, kill the Thundercats."