I've been using a Retina MacBook Pro 13" (early 15) and 15" (mid 15) and just picked up the xps 13 9350 with iris pro.
There are definitely some quality control issues but once you get a working model with no faults (I had one that wouldn't reboot and had terrible coil whine, one that had loose trackpad and yellow tint on screen but this could also be because of Amazon's shitty packaging where the laptop was in a box with only some brown paper crumpled in) - atleast they took them back no questions asked. I'm amazed how far windows laptops have come along.
The only real downsides are that it power throttles (and thermal too, but I placed my own aftermarket thermal paste and it doesn't cross 66 C on full load now) due to the iris GPU itself consuming 18W at it's rated turbo boost with the SoC's TDP being 15W (long turbo) and 25W (short turbo). Perhaps go with the i5 model that has the HD 520 or the new 9360 that has kabylake with better thermal and power consumption (HD 620 is roughly similar to HD 540 but won't throttle). You can also use Intel's XTU to undervolt and better battery life and throttling if you're going to use windows.
Linux runs flawlessly, infact so does OS X if you can replace the wifi card. AMA