I got my XPS 13 today. The trackpad's awesome. The screen would be, too, if it didn't have Mura (white dots, just like my 15" rMBP), so it's DOA.
The form factor is insanely great.
However, what's NOT great is the cooling system. It's not the placement of the grill - it's the simple fact that on the i7 model I have, the fan runs PERMANENTLY at medium to high setting. It's so insanely loud, forget about using this in a quiet office, a classroom or a library. I thought I had a defective one, but nope - lots of owners seem to be complaining about it. Why the reviewers all are saying it's quiet beats me. I've never had a laptop that was this loud.
Complete and utter fail -> goes back tomorrow.
Dell has a long history of fan control issues with their laptops. I'm not bashing them, I've been a customer since almost Day One. It's common to see Dell go through a dozen revisions of the BIOS to try to balance temps and performance.