Unity is garbage. Its Ubuntu's default desktop environment. Previously, Ubuntu shipped with Gnome or Gnome2, which were very popular options. Gnome 3 and Unity are horrible, horrible desktop environments, and unfortunately, Gnome 2 is no longer an option.
Starting in 2011, with the forced installation of Unity, Ubuntu started to become less desirable for me personally. Mint, OpenSuse, and Fedora just haven't been as reliable as Ubuntu was in the past (Ubuntu 10.04LTS, as an example, was the first and only Linux operating system I ever ran where after installation, everything worked on every computer I installed it on - wifi, sound, video, etc.). Nothing has been the same since.
Combine the oddball decision to force Unity on users with the almost simultaneous release of Windows 7, and the death rattles for Linux has begun.
Its really a shame. For the first time in many years, I spend more time at home on a Windows PC than any of my other computers. I have a Mac, 5 Linux PCs, and a Windows PC.
I agree with you regarding Ubuntu. You must admit that Canonical and Gnome were ahead of the curve, though: They alienated their users by forcing a crappy, universally-loathed UI upon them before MS did the same with 8.
But you know, if you're judging by the UI, that's really not Linux, anyway. You can build Linux to suit whatever fancy you like. If you're used to Ubuntu but hate what Canonical did to it, you can just download a copy of Ubunty Wheezy and go from there. If I had to build a Linux desktop today, I'd probably start with CentOS or Fedora because I'm more used to RedHat.
My point is that the GUI is not Linux. If you hate Ubuntu's, you can build your own, or use someone else's, or use none at all.
That being said, Linux was never an ideal platform for a GUI-based desktop system, anyway. That's not what it does best. It became semi-popular on the desktop for philosophical and economic reasons, but also because Windows in the DOS lineage that most home users and many really small businesses used was such a festering pile of crap from Win95 forward to Me.
A lot of people, myself included, just got tired of the instability, and started using Linux just to have a stable platform that didn't crash and burn two or three times a week.
That changed when MS released XP, which was far from perfect, but at least could rack up uptime measured in weeks or months, rather than hours. Then came 7, which is superb; and 8, which is even better except for the horrid Metro interface. XP to a good extent, and 7 even more so, brought stability to the Windows experience.
Linux is still a viable "desktop" platform for people with a limited set of specific needs, such as SDA. It's also a good platform for special-purpose machines. I'm currently playing around with a point-of-sale system on a Fedora box for a friend of mine who has a hardware store and needs a machine just to run the POS functions. So I'm tinkering with uniCenta oPOS on top of Fedora. I'll also wind up playing with it on top of, at least, Debian and CentOS before I'm done.
So basically, I agree with you regarding Ubuntu, and I also agree that the need for Linux on the desktop has receded as Windows has actually become stable. But remember that Ubuntu is not Linux. It uses Linux, but it's not Linux.
-Rich