I also loved Windows Vista, the system itself was quite buggy and slow but the UI was absolutely amazing and clear.
What changed is that by Windows 7 launch, PC specs had caught up with system requirements and WDDM drivers had matured and were no longer crashing all the time. So the first impression was very different.
I hated that UI so much, I'm glad I barely had to use it (that it was slow was due to underperforming hardware, esp. laptops, for which it arguably wasn't meant to run on).
In the meantime, I'll migrate away from anything Apple, for two reasons: 1) I don't want to be dependent on a US company for my OSes, and 2) thank you very much Apple for this design choice making #1 a lot easier. But what I cannot say is 3) it is slow and buggy. I mean, the design itself is bad if you ask me, but the OSes aren't slow. The hardware can deal with it.