On the fifth criterion, overall impression, I give Ubuntu all five stars again. I do so, however with the following provisos.
Ubuntu is not without its bugs. Because it's built on Debian, it can become unstable. Usually, that only happens when you are trying to run more programs than you have actual physical memory to run properly. Given the grand scheme of life in the world of Linux, Ubuntu is a lot more forgiving when it gets temperamental than most distributions. It's definitely not as unstable as standard Debian, so if you are hooked on the world of Debian, Ubuntu is a way to have Debian's versatility and not have to deal with Debian's instability.
The lack of a root user account can be incredibly frustrating. While there is technically nothing in Ubuntu that absolutely requires the root user account, some programs, such as X CD Roast simply won't work when you try to run them outside of the root user environment. As a matter of fact, X CD Roast can't even set up its configuration file in any other mode than root user. As I said above, for every package that gets persnickety about the lack of a root user account, there are five others that could care less. With Ubuntu, one has to use K3B as a GUI CD burner. No big deal since K3B actually works and looks better than X CD Roast. The point remains, that one small glitch can be incredibly annoying.
Other than those two bumps in the road, Ubuntu is a distribution that lives up to the ideal of its creators. It is very user friendly. It is just right for the newbie and the power user alike, given said power user can handle the no root user proviso. It's not harnessed with a set of non-removable training wheels like Ark Linux, but is just as friendly to the newbie. In operation, it is as flawless as one could expect a Linux distribution to be. Also, considering you can get it in Gnome, KDE, Xfce and Educational varieties and install them without further need for installation of more, it is truly the distribution that can give you what you want right out of the box.
As I said before, of all the distributions I have tested so far, Ubuntu comes as close as any to making me reconsider using Slackware exclusively. Considering how long I have had Slackware set up on this machine. That says a lot.
As I said in the intro, "Ubuntu: funny name, serious system!"