I've only done a couple of them so far but for the two I have done:

Copperbell - I'm someone who actually appreciated the concepts behind all 3 bosses. I think they could have done some interesting things had they continued with some of these ideas, or at least executed what they had here better. But the way the fights were actually done was 100% coma inducing, and they also felt very out of step with a lot of the fights even a little bit later in the game. Either the fights needed to live up to their unique mechanics or they needed to be redone completely, so the latter made more sense. I'll miss the old ones but really only in a sort of rose tinted glasses, what could have been, way.

Toto Rak - This one really feels off to me now. I get that some people didn't like the twisty, windy alternate paths and what have you, but I actually enjoyed it. Even if you straight lined it, it felt more like a real old school RPG dungeon to me, and there were those couple of switch backs in the pathway that new players always fell for.. and that always made me smile. Overall design aside, what I really miss the most, though, is just how dank, dark and dangerous it used to feel. It used to be the sort of place you would only go to if you absolutely had to but now with the bright sunlit clearings and greenery it feels more like somewhere you'd go on a picnic. I can understand the new dungeon design but the new lighting and visuals completely killed the mood and vibe it had before.