When it came out it was a substantial UX regression from Gnome 2 and it took a few releases to even reach feature parity.

The same thing has been seen with KDE 4 and 5, Gnome 3, and how long LXQT has taken. Users hate experience regressions passionately, and will actively hate projects that depreciate or replace their workflows, sometimes for years, and sometimes forever.

When Unity first became the default DE on Ubuntu, it was unusably slow and buggy on my computer. (This was actually an improvement -- in the previous release, Unity would immediately crash, so I had only seen it in pictures and videos.) Gnome 3 Classic was still available as a fallback, but it still wasn't the same (to many changes, to much CPU), so I switched distros. (I didn't know enough at the time to install a DE myself.)

At the time, I was quite unhappy at Canonical for making their OS so difficult for me to use. I felt that I was being totally left behind, with a machine that was just old enough that it wasn't worth it to them to support it.

1 or 2 years later, I tried a newer release of Ubuntu on that machine. Unity was definitely more stable than before, but it was still frustratingly slow, and had sprouted the weird, unwanted amazon search feature. I continued to be disappointed that the default install of Ubuntu had become so needlessly graphics-intensive, and haven't played with it since.

---

One other gripe with Unity -- I really didn't like how it thought that applications were more important than windows. It was difficult to switch between 2 or more windows of the same applications on the same desktop. The icon on the taskbar just showed a tiny arrow for each window. You had to hover over it before it would show buttons (icons? previews?) of each window that you could select. Alt+Tab was the same. You could only rotate between applications, but if you held it down for a moment, it would show the windows of that applications, and there was some way to pick between those on the keyboard.

I really didn't like that. I would often have 2 or more terminals open, or text editors, or file browsers, and I would want to switch to the one that I had least-recently used, and I would have to do this whole dance of pulling up the application, waiting to see the individual windows, and finally picking the one I wanted. The 2-3 seconds that took were very frustrating, since I knew that I had used to be able to hit Alt+Tab a couple of times to go directly to the window I wanted.

I have the same frustration every time I have to use an apple computer. It bugged me enough that I read through the keyboard shortcuts settings and learned about Cmd+Tilde, which helps, but is still very frustrating. I want a window! Why does it take two different kinds of keyboard shortcuts to get to the window I want!

---

Between those two troubles, I am happy to have avoided using Unity.

Never had any qualms with the design, it was just too heavy for most machines I run ubuntu on. Felt like a laggy remote desktop connection.

I think it was too simple and non-customizable for Linux user's taste, but it was that same simplicity that made it a perfect OS for a public computer or for parents who only use simple apps.

I can't understand any of it. Its looked the same to me for years and years. Other distros look a little different but nothing substantive is actually different that I ever notice.

Agree. The last versions were pretty and (still) very stable.

Was because of the slow screen refresh, and the shitty metro look that announces "im like windows, but poorer".