I agree, Synaptic package manager is great. I was also a long time Mandriva user before I had to switch distros for work. To make my life easier I made the switch at home as well (to Ubuntu for desktops and Debian for my servers). I just figured that for support purposes they would have gone with a distro that is french based. I am a ubuntu fan but I do try out Mandriva's newest versions because I used them for so long and it isn't a bad distro. Just seemed a little odd is all, although I am sure they will not regret going with ubuntu.
I am surprised that they didn't go with Mandriva, seeing how I am pretty sure they are based in France.