I jumped on the UP4-TH first, a few minutes after the CustoMac buyer's guide was published. With a few of our reviews, he finally removed UP4-TH from the list of recommended mobos, but only after 3 weeks when we all realized that the drivers were never going to be published. At least he apologized to us who jumped on the bandwagon, but now I'm stuck with a mobo that doesn't support 4 of the USB ports.
So with the UP4-TH, you will have two working USB 3.0 ports, while all the other USB ports will not work. However, there are two USB 2.0 headers and one USB 3.0 header on the mobo itself, so you can add three cards (or front USB connectors) to complement the lack of USB ports. For example, I have two USB 3.0 ports on the front of my chasis that plugs into the motherboard, and two USB 2.0 cards that plug into my mobo.
Also to note, all USB ports work in Windows and Linux. Only Mac OS X cannot utilize some of the USB ports.
In lieu of the UP4-TH, you can get the more expensive Gigabyte UP5-TH. But if you don't need the thuderbolt ports, why not just get the Z77x-UD5H? It's got more ports than the UP4-TH, it's cheaper, and it's fully supported (but it doesn't support thunderbolt).
One thing to note: I missed the fact that the UP4-TH does NOT have wake-on-lan capabilities. It's something I use on all my machines, and I completely overlooked it because I was in dire need of building a new rig. Read all the specs. before you make a purchase.