I just bought a brand new Asus Ultrabook and installed gentoo with few if any problems. Lots of documentation on the Arch Linux and Ubuntu sites related to my laptop model were really helpful. The boot was a small pain but really only took a few hours to sort. If you're not willing to spend a few hours sorting something out, Linux on the desktop probably isn't for you anyways. I had it fully up and running in about a week with no tinkering for Suspend/Resume, Touchscreen support, or Audio, which were pain points in the past. I did spend a lot of time on the Intel wireless (I had to download the firmware manually and really it was more learning about Systemd and NetworkManager) and the Intel video chipset because the kernel parameters were customized. Also ACPI support for the backlight and function keys was a bit...messy. Still haven't gotten wireless printing working, and I'm fighting with Plymouth still.
FWIW, I have a linux NAS box I custom built using a Gigabyte motherboard about 3 years ago and had no problems with it either. It did have UEFI, but Windows 8 wasn't out yet so I don't know if that complicates things. More recently I built a couple of LTC miners using MSI motherboards with few problems. Those definitely had UEFI and weren't a big deal. The biggest problem was getting the ATI drivers to like my 4 video cards.