Ubuntu tends to come in three basic flavors, reflecting only a different desktop: Kubuntu features the KDE desktop, Ubuntu features Gnome, and Xubuntu the XFCE desktop. I listed these in order of resources required to run them. KDE is full of eye candy and most similar to Windows. Gnome is middle of the road but I just don't like it. XFCE takes the least amount of resources, thus can run on the widest range of hardware. And if you use XFCE on current hardware, it's that much faster. While there are even lighter distributions (distros), these are the three main ones.
History shows that the Ubuntus are solid, reliable distros, so much so, in fact, that you can generally install the release candidate early, without having to worry about what it will do to your computer.
DISCLAIMER: as Ubuntu warns, do not upgrade production machines early.
I have been running Xubuntu 10.4 since it came out and I'm quite satisfied. I decided to upgrade a machine to 11.04 (Nutty Nincompoop) to see what would happen. In case you have been following the news about the early releases of Nutty, you know there's a huge controversy over the new Unity desktop. There is even grumbling over the new Gnome desktop. Understand that regardless of desktop choice, the underlying bits are the same. You can choose to run whatever desktop you like - you're not married to only what comes `in the box'.
My upgrade process took about an hour but your time will vary because of download and processor speeds. Since I ran an upgrade, I did not have to deal with Unity, it simply booted right into XFCE from where it left off. As for Unity, I used it in the netbook-optimized Ubuntu distro and hated it immediately. It struck me as training wheels that weren't necessarily required but possibly would have helped rank beginners.
If you are upgrading plain old Ubuntu (Gnome), you'll boot into Unity first, then you can switch to Gnome.
If you have a separate Home partition, make sure there is at least 2g remaining on the OS partition if you're doing an upgrade. If you have way too little, it will warn you, but it never hurts to have too much.
I dumped Unity and went with standard Xubuntu on the netbook and never looked back. It's supposed to be more efficient in terms of the screen but I found no advantage there either. Unity seems like one of those times when someone had a `good idea' and it mistakenly made it into the product's final release. In fact, no one I know has nice things to say about Unity. But that's just my opinion: use it and decide for yourself.
SO WHAT'S IT LIKE?
You may well ask what it's like.
We just did.
And well you may. When it came up for the first time, I noticed just about no difference at all from my former XFCE setup. It installed the Orage clock/calendar in a panel, which I removed. That's about the only noticeable difference thus far. Again, your mileage will vary with upgrade and desktop, but only with the express written consent of the National Women's Volleyball League.
I was so tickled that I upgraded another machine. Again, remember that this is pre-release by a few days and don't do this to any important machines. That said, there are no show-stoppers at all. Everything works as it is supposed to. There is a lot more included in Settings, which XFCE desperately needed.
Thus far I have not been able to locate a menu editor. This is not a total surprise, as XFCE has had no practical way to alter menus in quite a while (that didn't involve dual degrees in quantum physics and string theory).
Thus far, the upgrade has gone the way most prior upgrades have gone: quickly, quietly, without grief, and largely not too different from its predecessor.
I'll have more as I use it more.
I just updated a dual-monitor system and was very pleasantly surprised to discover that not only did Xubuntu detect the dual monitors, it had a few small panel settings to make things easier. It has settings for transparency (which I will never use) and allows the panel to span more than one monitor. Little things like this are welcome additions.
Not sure why it felt the need to remove Tellico, my favorite video collection manager, but I reinstalled it after.
I also discovered Broadcast Messaging, which is something that escaped me at first. After a brief search, I discovered this is a setting to give social network status messages when you log into the computer.
Being the absolute head of the anti-social network, I found no use for this at all, even though it was enabled. The day I need my computer to let gobs of people know I have logged in is the day I have stopped using the computer.
Your mileage, of course, will vary.