I'm happy to believe that iTunes on NT is terrible, but the missing datapoint is whether iTunes on Darwin is also terrible. That is - is it a badly supported platform, or is iTunes just awful?
From my time with a mac, iTunes was bad on a mac. But at least it follows the platform UI (as much as any media player does). iTunes on windows insists on trying to look and feel like the mac version, which is very out of place on Windows. Safari for Windows did the same thing when it was around. Pulling in Apple's fonts and Apple's font rendering is part of the problem.
It was far less glitchy than iTunes for Windows, but no longer exists on macOS. years ago Apple split it into TV app, Music app, and they do device sync is through the file system Finder app.
Generally the replacements still lack many iTunes features many years later, but iTunes really did grow into an unmanageable monster.