I bought an Ouya shortly after they first came out in stores. I love the design of it. It's very small and neat looking. However, I found the system to be rather horrible to actually use.
The games that were in the store were all app store games with a few super cheap self published titles as well. I actually bought it to be a complete emulation machine, but I found the lag from the controller rendered the entire thing unusuable.
I tried and tried to make it work, but that half a second delay or so was just too much to deal with. I ended up selling it on Amazon for dirt cheap.
With that being said, there are a lot of people really happy with the machine and its emulation capabilites on the Ouya forums and such. It just didn't work for me. I would spend the money and buy a cheap used laptop for emulating. I think it would work better.