I installed Ubuntu on my new desktop in February. Here are some thoughts on the experience after three months.
My initial motivation was that I'd decided to spend some time participating in the Ubuntu project to see how it operates, and I needed a running install in order to troubleshoot and potentially fix bugs. I also have an Ubuntu home theatre machine, but it's essentially headless (just runs xbmc on the TV, with no usable X desktop), so anything else requiring a graphical interface is not usable.
Initially I tried running Ubuntu in a VirtualBox VM under Windows 7, which worked fine but the added slowness and extra GUI hoops were annoying.
Almost everything I do under Windows I can do under Linux (or Mac), with the significant exception of gaming, and I had plenty of disk space. Also, I was curious just how Ubuntu would work on the fairly new hardware I'd purchased -- I've run Ubuntu before. So I figured I might as well try a dual-boot install.
The install itself was quite simple, as expected, as I don't have any particularly odd hardware from a base install perspective. I created a bootable USB stick, booted off it, went through the installer, resized the partition on my Windows data drive to get some space, and went through a normal install.
Everything worked as expected from the start, but just using VESA video drivers, and I wanted to get the AMD native drivers working to get full hardware support since I had this nice new video card. So I installed the fglrx-updates package which provides the AMD proprietary hardware drivers. This isn't ideal from a free software perspective, but I'm glad they at least provide usable drivers in some form. I had to do a bit of debugging to get the drivers working the first time, as they require that Linux kernel sources be installed but for some reason this isn't listed as a dependency on the package. Eventually I figured that out by running the package install in verbose mode, and things have worked great ever since.
I tried a few different display managers as alternatives to Unity, including Cinnamon and Enlightenment E17. I really liked the stripped-down look and feel of Enlightenment, but it seemed unstable and kept segfaulting, which made me sad. So I've stuck with Unity for now.
One thing I did do after installing Ubuntu was to remove the Unity Shopping Lens, which provides the feature that returns Amazon search results in the Dash search box whenever you do a search for something on your machine. Many people have a lot of privacy issues and other concerns about this feature, which I acknowledge and share, but the primary motivation for me was annoyance at having all sorts of stuff I don't care about coming up when I searched for things on my computer.
For my normal application usage (browser, terminal, torrents, videos, photo and file management) I've had no problems with any of the Linux alternatives. I'm using Chromium (the open source version of Chrome) instead of Firefox, VLC for videos, Shotwell for photo management, and Deluge for torrents. I've tried a few email clients, but none were entirely comfortable, so just use webmail. And my RSS reader is still Tiny Tiny RSS, which I wrote about in March, and that's in the browser as well.
Regarding gaming, I've installed the Linux version of Steam, and it seems to work fine, but there are few games available for Linux that I'm particularly interested in at this point. I'm most interested in MMO titles, both role playing and first person shooters, particularly if they're free-to-play or freemium model, but I haven't seen any on Linux yet (it's possible I missed them). Most games available seem to be smaller indie titles, and not much appeals to me. I'll keep looking, but for now I reboot back into Windows when I want a gaming fix.
Interestingly, since I've started running primarily Linux I haven't been feeling the need to play games as much, so I tend not to boot into Windows much at all. This is likely in part because the games I'd been playing had become a routine more than actually holding my interest. I'm not particularly unhappy about this shift, I have a lot of other things I should be spending time on before gaming, but it's been long enough that I'm interested in getting back to occasionally playing some games. We'll see how this trend continues through the rest of the year.
So, for now I'm a happy Ubuntu desktop user. I'll let you know if that changes.