Most of the issues with USB drives have been fixed. Installing games to external storage is "in Beta" but has been working for me with no issues.
I have a 16 gb usb drive with about 10 gigs of games for emulators and about 5 left for additional OUYA games. I havn't had issues with storage since they patched that in.
That said...use a file manager app, either Filepwn or Astro etc...to look for your drive. Usb storage of roms and media has worked from day one but there was a bug for a bit where the drive didn't show up in the "storage" settings menu but it does now. I think I set up the emulation about a week in and I've always used a USB drive...swapping a 4gb drive for the 16 I use now. Some folks use a HD. In any case they work and you can install games to external drives now.
@Slippyblade. If you are worried about the controller, they have a revised controller comming out with new units that addresses many peoples complaints or so I read. Those with issues are told to RMA them...but My controllers are fine...the only lag I've had was when I got too far away, 15-20 ft and my batteries were almost dead. But there is no reason not to use a PS3 controller if you don't like the stock one. I have also used an aftermarket logitec wireless controller. But in the end I prefer to just use the OUYA pad.
@mike. If you search for OUYA on the forum here you'll find my initial review and that I was pretty happy with the system dispite some negative thoughts from others. I like it more than ever now.
As for games. There are lots of good, fun games...and it is even easier than ever to find them.
Rather than make suggestions of specific titles, (you can find some in my initial reviews), I'd suggest you spend some time trying out the top games in the "trending" section of Discover. They are all Free to try and many of the good ones can be had for $5 or less.
I will mention one that I was playing tonight though:
Twin Tiger Shark It is a pretty fun virtical Shmup
AND it has TATE settings. I thought that was cool.
No I didn't turn my HDTV on its side but it still made me dream of sticking it in a cab with a huge HD screen.
Another great aspect of playing the OUYA is that there are more and more games to play "couch multiplayer". If you have buddies/kids check em out.