I have the previous (2nd gen) Dell XPS 13, with 8GB DDR3 and a Core-i7 (dual-core, with 2 threads/core).

Wonderful machine. Second fastest in the house, though most of our machines are older ones. Plays any def video just fine, and that's under Linux with older drivers, rather than the latest/best that may be on offer for other operating systems.

A buddy of mine liked it, and bought this year's version, with full touch screen. It works wonderfully under Ubunbu, touch and all.

One downside of the one I have, is they mis-designed(*) the left side (as viewed from the user's point of view) USB3 port --> it really can only operate reliably at USB2 speeds, not USB3 speeds.

The newer model that my buddy has behaves better.

(*) The left side USB3 port is connected via a long internal ribbon cable with parallel conductors rather than twisted pairs, thus the issues with super-speed USB3.