All actors playing Vulcan's should have watched Leonard and Lenard in action to show that you can get emotion and a gravitas in your performance without coming across as emotional, and in fact be quite witty and sympathetic. Too many actors played Vulcan's as mindless machines, especially in TNG.
Had TWOK made Saavik's half-Romulan ancestry canon then it would have better explained her performance. Curtis was quite flat and boring, she had the stoicness and emotionless part of it right but Saavik goes immediately from having an edge and being interesting in TWOK to totally forgettable.
I don't think Russ was bad as Tuvok, I do think poor use was made of him in Voyager, same as Chakotay really, who started with claws and fire then was totally emasculated under Janeway, in a way Tuvok suffered the same fate in that he was meant to be a voice of reason and sage like and just plain wasn't. Episodes that should have raised his character and made him interesting singularly failed to. Examples being Tuvix, Prime Factors (which would have been good but was never followed up on), Learning Curve (same as Prime Factors), Innocence, Flashback, Alter Ego, Riddles... I could go on.
Rise and Gravity try to make him more endearing but they just don't really work. Flashback was hugely disappointing to me on several levels but amongst other things it could have better expanded on Tuvok's character. I think part of the problem was having Neelix as his "McCoy" if you get what I mean. In a strange sort of way Neelix was really quite racist in his refusal to accept Tuvok for how he was. In TOS you had McCoy being openly racist but Spock always came back with retorts and you knew later that it was banter amongst friends. Tuvok is just continually irritated by Neelix as it the rest of the audience but not in a way that does anything for Tuvok's character.
Anyway I digress. Returning to ENT, I enjoyed T'Pol's character, like Ryan she avoided her character just being used as eye candy with strong performances and ENT in general made Vulcan's seem more real IMO. They weren't perfectly portrayed by any means but at the very least it was refreshing and an actual change of franchise direction rather than a slightly different coat of paint.