I received my XPS with Ubuntu today. The first thing I will say is that when the Fedex guy delivered it he asked if Dell was having some kind of liquidation sale because he has delivered more Dells today than ever before.
Read the review at ubuntuforums
I think Dell has done a good thing with this system. They obviously made an effort with resolution detection (which was going to be sore no matter what) and did an excellent job of keeping the crapware off the system. If you want a machine that's going to run all the apps you need and do it well, and without having to research endlessly for compatible hardware to make one yourself, this machine is good for you. I have seen nothing that makes this a deal-breaker for the average user…assuming they don't want to enable 3D out of the box. That still takes some skills.