Having received my first Intel NUC unit on Friday last week, I thought I'd just give some feedback on how I'm getting on with it.
I ordered the DC3217IYE (2xHDMI+GigE) model, board version G76540-201. To it I fitted 2x 2GB of 1.5V DDR3-1600 RAM and a 32GB mSATA SSD, both from Crucial.
I connected it to my Panasonic TX-L42E5B television and initially booted from a FreeBSD 9.1 amd64 installation memstick to check how well the hardware was supported, as I may purchase some of the upcoming Celeron-based NUC's to build little FreeBSD network servers. Everything was detected just fine. The FreeBSD kernel boot messages are here.
One minor issue was that the standard 80x25 VGA text mode that most PC's boot in was not properly sized on my 1920x1080 television. The image was too large and a few lines and columns of text were lost off the edge of the screen. Disabling overscan on the TV didn't make any difference. FreeBSD's VESA driver reported that a 1920x1080 mode was available for the console, but this was also oversized on the screen.
I then rebooted and entered the BIOS setup to check out the options there, where I noticed that UEFI boot was enabled by default. I prepared a Windows 7 x64 installation USB stick with the necessary modifications to allow it to boot and install in UEFI mode. Windows 7 installed with no problems at all, as did all the latest drivers from Intel's website. The couple of hundred Windows updates took a very long time to install, perhaps due to the network performance issues reported in other threads (when the HDMI port closest to the ethernet port is in use).
Windows 7 boots very fast, about 3 seconds from the Intel splash screen to the login screen. This is the first system I've built with SSD storage, so I'm well impressed with that.
I did also try out the Intel Rapid Start feature, but resuming from hibernation required pressing the power button on the NUC, whereas resuming from suspend could be done from the wireless keyboard. I opted to remove the Rapid Start software and recovered the 4GB of SSD space that the hibernate partition required.
The Windows Experience Index of this system is 5.8 which is only 0.1 less than my main DX58SO + i7-920 based desktop, although that score is dragged down by conventional 7200rpm disk drives.
Overall I'm quite happy with the unit, although the HDMI+ethernet issue does cause concern. I don't currently have a need to use two screens so I can avoid the problem, but it would be nice to run a NUC as a dual-screen desktop. The nature of the problem and the fact it can be resolved by using a connector physically further away suggests to me that it might be due to electrical interference, but I suppose it might be an interrupt-related thing.