Lois and Clark certainly cannot be described as the most accurate portrayal of Superman but from everything I have seen of the Man of Steel (including Superman Returns) it wins hands down for entertainment and believability.
The main reason for this is Clark Kent, who was the main character of the show; not Superman. We see Clark as a human being who has our emotional failures and various other flaws. The show details his struggle to overcome them. Superman is very much his disguise the cape allows him to use the powers he is capable of using for good, as an icon and so those he feels for are not affected by the forces of evil. In the films, Kent is the disguise. I find that a bit too radical. It is acceptable to have this identification in The Batman series as Wayne's playboy lifestyle is the cover for the true character of Bruce Wayne: Batman. But to have Clark Kent reduced to a clumsy fool is a bit far-fetched for my liking.
Then of course we have Dean Cain and Teri Hatcher. What superb casting. The on-screen chemistry from these two was of such a high acting calibre that they both should have won many, many awards for this show. The writing for these characters also needs to mentioned as it is of such a quality standard. There is truly a sense of complete attraction from both characters to each other but both are too shy to express it. What was so brilliantly ironic was that when Superman, neither character showed anything other than attraction to the other - superb writing. We are also allowed to venture much more into the character of Perry White, whose portrayal by Lane Smith is so witty, funny, all knowing and brilliant. The best Perry White there is ever likely to be.
I think the real genius behind The New Adventures of Superman though was Lex Luthor. Never before has a version of Luthor been so evil, so calculating so egocentric and so intelligent. I think Gene Hackman was a fantastic Lex Luthor (far better than Spacey, whose average performance took me by surprise) but John O Shea's voice and mannerisms were perfect. Of course, Clark saw right through Luthor's Good Samaritan public façade and this made the story of his brief affair with Lois Lane all the more watch able. I think the writers perhaps identified that they made a mistake killing him off at the end of the first season as from then on Superman had no full-time enemy which in the long-run cost the quality of episodes. Having said that, the season two episode "The Phoenix" in which Luthor returns is perhaps my favourite episode. I'm surprised that he wasn't used more often after that because he was in jail, not dead. It would have made excellent viewing watching Luthor escape and then having to build his empire again from nothing. We could have gotten a taste of how truly evil this character could be.
To wrap this assessment up I will say that every other version of Superman I've seen, I find myself cringing at certain points. Not in this one.