Having got my new Dell XPS 13 with Intel Broadwell finally this Friday, some initial thoughts about it.
The device feels very good when holding it in the hands for the first time. Also the design is very good, but that should be clear given the price of the devices. I was positivily suprised about the amount of options in the UEFI of the device. Dell really allows for a lot of fine thuning there and I still have to experiement with certain settings in the future. For example there are three different modes on how to use the battery of the device. Having set it to the "I use mostly AC power" seems to not use the full battery capacity when charging in order to reduce wear on the battery and hopefully preserving much of it's capacity for the times it is needed.
I originally intended to stick to Xubuntu for the device, but already after booting into the live image it was clear that Xfce 4 does not yet properly support HiDPI systems. You can set the DPI used for font scaling manually, but the rest of the UI (icons, borders, etc.) does not scale with it. So after quite some time with Xfce it was time to consider alternatives. My plan B for this case has been GNOME 3. So trying out Ubuntu GNOME. Despite all the bad opinions about GNOME shell in many Internet posts, this shell works pretty well for me.
During the inital testing three problems with the XPS 13 and Ubuntu GNOME became visible. The two were immediatelly visible. Namely both sound and WLAN/Bluetooth did not work at, there were simply no devices found. For Bluetooth and WLAN the solution was to install the proprietary Broadcom driver, which unfortunately taints the kernel (due to being propritary), but works well so far. For the sound it seems to be related to the interface used by the chip. Recent Linux kernels use the ACPI identity "Windows 2013", which in this case made the sound chip using an I2C interface instead of the well known HDA interface. It seems there is currently upstream work in progress to address this issue properly (related bug report on Launchpad). As far as I understand it, this issue is also not specific to the XPS, but might also appear on other Broadwell ultrabook systems.
The third problem showed up relativily soon too in the form of font corruptions and system lockups. From the symptoms I strongly suspect it to be caused by bugs in the Broadwell graphics driver code. Since Broadwell is pretty new, the driver stack shipped with 14.10 seemed to not having stable Broadwell support yet. Since 15.04 is still in Alpha and not yet ready for productive systems, I am currently trying the Oibaf PPA to get an updated graphics stack into 14.10. The results are so far very promising. I did not see any font corruption or other render problems.
Overall I am pretty happy with the machine. I am confident that the remaining problems will be solved too, given the fact that the hardware platform was just recently lunched.