Upgrading from Ubuntu 10.04 (Lucid) to 12.04 (Precise)
My laptop is a couple years old, but the battery is still good, the screen is plenty big enough, and it's the computer I use most often. After years of Ubuntu, I went back to Fedora a couple of weeks before Christmas. Knowing that the newer desktops were radically different, I grabbed that ( to get used to GNOME3 ) and stuck an early Ubuntu 12.04 on a desktop for my wife to get familiar with.
Neither of us could make the transition. Perhaps we're just old and set in our ways, but the new method doesn't do it for us. Xfce seems pretty similar, if you set it up right, so I figured that when 12.04 came out "for real" I'd stick Xubuntu on. It's working fine at this point (late May, 2012) but I did have an odd experience on my laptop.
I didn't end up getting a clean install. I put a later beta 12.04 iso that I'd downloaded a few weeks before the official launch and just updated it. I then installed the xubuntu-desktop package, and the Desktop computer (the one my wife and I both use) was fine. My laptop seemed to operate fine with Unity, but I hate Unity; I dislike Unity even more than I dislike trackpads, and that's saying something.
So when I threw xubuntu-desktop on the laptop, I noticed something weird. One morning before going to work, I'd shut the lid. But by the time I went to fire it up on my lunch break at work, it was dead. For some reason it wouldn't sleep any more. I booted back to Unity, and tested, and it worked fine. The prospect of my laptop either running a crappy desktop or having a dying battery all the time was not one I looked forward to.
I also noticed that the screen brightness was always full tilt unless I manually adjusted it, and my changes were not persistent after a reboot. That didn't seem to matter WHAT desktop I used (and I'd also thrown on LXDE and KDE at some point) — they were all equally wonky. On top of this, removing Lubuntu didn't get rid of the Lubuntu splash screen I saw while the laptop booted. Nor did getting rid of KDE remove the KDE looking login screen.
I'm happy to say that a FRESH CLEAN install of Xubuntu behaves as I'd hoped it would. The laptop sleeps when I shut the lid, the screen is as dim as I left it before a reboot, and my desktop environment does not suck. I'm a very happy camper.