An hour or so ago, I got the notice that Lollipop was available for my 2013 Nexus 7 tablet. Despite my reluctance to embrace x.0 versions, I decided to have it downloaded and installed.
You can see visual differences here in this Ars Technica article.
Naturally, the update took a while, and there was a bit of time involved as it was "optimizing" applications.
I haven't spent much time at the moment. So far, my most consistent experience is when I unlock it, by pressing the lock icon and sliding it, which gives me the camera. Perhaps, they want me to see how much better the camera is. I really don't know.
The system icons at the lowest part of the display look less indicative of their functionality. The joined rectangles were more of a clue of the multi-tasking manager than a single square.
Google Play seems okay when updating applications. I'm not sure it works better but it looks better. Perhaps, that's the thing--we're to be enraptured by its new look, and will forgive any lingering problems. Apple tried that and it didn't work. I get the feeling that Google never tests anything with regular people who aren't directly connected with the company. Apple does it somewhat, but things aren't always intuitive any longer.
I look forward to finding if performance is improved. I've read that it could be smoother and faster, but until I experience it in real life, I'll continue my skepticism.
So far, the delay from booting is still there. It may be diminished somewhat, but I need to let the tablet sit a while before I do anything.