Frankly, I don't like Ubuntu, but I am still happy about this decision. Ubuntu is the most Windows-like distro from what I've seen, and this should allow users to migrate somewhat comfortably from the Windows world to the Linux world.
The thing that I'm really happy about, however, is that I can now buy a Dell Ubuntu laptop with the knowledge that I'll be able to replace the Ubuntu install with a Gentoo one and still have all the necessary Linux drivers. No longer will I have to be months behind bleeding-edge hardware in order to ensure that everything will work in Linux. Of course, this might take some time to occur (for a while I'm sure that they will only release well-supported hardware), but if it's successful, hardware producers will eventually be compelled to release Linux drivers alongside Windows ones.
Ubuntu is highly popular, and is growing very quickly.
Moreover, it cares more about enabling nontechnical users (doctors, lawyers, etc) to get work done than any other distribution I've seen. Most of the advances in Ubuntu I've seen have been in the direction of making it easier and easier for people who don't know what an operating system is to be helped by Linux. (cf. Windows migration tools that automatically create a dual boot system, and crawl the Windows partition to find bookmarks, email contacts, etc).
As such, I think it's the most suitable distribution for a mainstream vendor to adopt for sale to mainstream users.
The thing that I'm really happy about, however, is that I can now buy a Dell Ubuntu laptop with the knowledge that I'll be able to replace the Ubuntu install with a Gentoo one and still have all the necessary Linux drivers. No longer will I have to be months behind bleeding-edge hardware in order to ensure that everything will work in Linux. Of course, this might take some time to occur (for a while I'm sure that they will only release well-supported hardware), but if it's successful, hardware producers will eventually be compelled to release Linux drivers alongside Windows ones.