Played a tiny bit of the first one in the 90s, but like you I only played through the trilogy just recently (in my case, last year) and on original hardware. I would not go so far as to say disliked, but you are absolutely correct that the controls are floaty (although not as bad as Sonic, but Sonic is truly awful) and it is often a challenge to tell where objects and platforms end. The third game has the weakest music, but I would consider a lot of the level and boss design substantially better. Overall, I think there is a heavy amount of nostalgia going on when it comes to the fans, but that is okay as long as we speak openly about it.

As for difficulty, we will have to agree to disagree. Only point that had me somewhat frustrated was the waterfall boss in the last game and that one had me stumped for some time (should have read the manual I guess?). Overall, I would still recommend the games as good for their time and among the better action platformers for their console, but they really are nowhere close to a masterpiece like Super Mario World that has pretty much perfected controls and you can tell exactly where platforms and objects start and end.