I was a big fan of the original, having watched it back as a kid in the early 80s during its original run. But I also watched a bit of it as an adult, and became acutely aware of its shortcomings. (The dialogue was haughty and stilted, like something out of William Shatner's nightmares. The characters were cardboard cut-outs, with almost no substance to speak of. And the series was very episodic, with very little plot or character development from episode to episode.) It was definitely one of those shows that seems better through the eyes of a child than it actually was.
With that said, I am very impressed by the new series. Whoever created it obviously took care to keep as much of the original series material and characters intact while remedying many of the problems. It's hard to judge a series based on one episode, but I think it has great potential.