I had it installed on my laptop. Overall it's not a bad OS. Incredibly easy install and faster than most distro installations. Also easy to use, has several different configuration wizards.
The problems I have with it are:
They tinker with too much.. to keep all of Xandros components and extras working you can only download their tinkered version, which are nowhere near the latest releases. They still use KDE2.2.
If you do decide to use other debian sources, you run the risk of causing Xandros extras to stop working..like XFM (xandros file manager) which in my opinion is really no better than konqurer in kde 3.x
You also may screw up the OS by using other sources.. I've done this several times.
Theres more but I'm at work at the moment.
I liked Xandros, I just hated they way they modified everything so I stopped using it.
By the way, if you purchase the $99 version you get a technology preview cd which is basically Xandros without quite as much tinkering. It has kde 3 and no XFM, but still has lots of other modified things in it.
Search the forum for Xandros, I osted another slightly more detailed post in one of the topics.