Now that the Haswell NUCs are hitting stores I thought it would be a good idea to bring up a few things that should help your experience with your new NUC. There's nothing Earth-shattering here, just tips & tricks that I've come across while working with the Haswell NUCs, as well as feedback from others. So here goes.
Memory: the Haswell NUCs use 1.35v memory. They don't support 1.5v memory. So make sure when you're buying your memory that you check the voltage. Also if you're looking for top performance you'll get better memory performance out of 2 matching sticks vs. a single stick. So if you want 4GB total you'll get better performance out of 2 2GB sticks. The trade-off is that you're filling both of your RAM slots, so an upgrade down the road means replacing the sticks you have rather than just adding a new one.
mSATA: It's really your choice for which mSATA to use but be aware that there are differences. I haven't found one yet that I didn't like, but different brands/models have different advantages. For example the Intel mSATAs are pricier but you'll get an mSATA that uses very little power. That can come in handy if you're doing something portable with it or if power consumption is a concern. In contrast a drive from Muskin (just an example) will be very fast but will also have a higher power consumption. Look at the specs and decide which one meets your price, performance, power requirements.
HDMI: Remember the Haswell NUCs have a miniHDMI connector, not a full-sized HDMI. So be sure you have a miniHDMI to HDMI cable or adapter. You can also use a DisplayPort to HDMI cable or adapter as the NUC supports full HD and audio over DisplayPort.
Drivers: All of the latest Windows drivers are available at downloadcenter.intel.com. Get them before you start and put them on a flash drive. You'll need them because your onboard NIC will not work out of the box on some versions of Windows so you'll want the drivers handy to install. You'll be glad you did.
USB DVD drives: If you plan to install your OS from a USB DVD drive (instead of the faster, easier flash drive method) be sure you have it connected correctly. External DVD drives typically require a 2nd USB cable for power in order to be able to boot.
Wifi in Linux: This isn't strictly for the NUC, it's for the 7260 wifi card. If you plan on using Linux with your NUC and you're using the 7260 wifi card be aware that wifi will not work out of the box. Bluetooth does but wifi doesn't. There's an easy solution here: http://wireless.kernel.org/en/users/Drivers/iwlwifi. It should get you up and running with wifi in just a couple of minutes. If you opt for the 6250 card (above) it should work out of the box in Linux and Windows.
That's all for now. If I think of any other tips I'll add them.