Now that we've had our OUYA for a while, I have to say that the OUYA is a cool and inexpensive toy, but it's somewhat superfluous right now, and will continue to be until it gets some more compelling content.
I've seen a lot of chatter on the internet from folks who have incorrect assumptions about what the OUYA is supposed to be. Some people are assuming it's a Playstation/Xbox/Nintendo competitor, and are dismayed at the low-end graphics and the lack of AAA titles. Some people are assuming it's just a way to run cell phone games on your TV, and don't know why they should bother, since they already have a cell phone.
The OUYA is not supposed to be a top-tier console; the tiny size ought to be a dead giveaway. And it's not just for cell phone games; games like Bombsquad and Towerfall work best with four friends sitting around the same screen.
The OUYA is supposed to be a console platform with a low barrier of entry for independent developers. If I personally took a week off and locked myself in the house with a copy of Unity, I could have a game up on the OUYA store by the end of the week. (Disclaimer: I don't actually know how long the OUYA game review/approval process takes, but I've heard that it sometimes takes mere hours.) This is great for small developers; it lets you get your game in front of the public at minimal expense.
The problem is that the console doesn't offer a lot to the actual gamer, which is the person who's supposed to be buying the thing.
Are you interested in cheap console games? The existing consoles already offer a variety of cheap games for download. I could go right now and download a variety of PS1 classics that are priced less than some of the less-polished efforts available on the OUYA.
Do you like indie games? Again, the digital download stores for the big consoles have you covered there as well, though you won't find a lot of quirky, lone-developer, "I did this because I thought it was cool" titles on the big consoles. For those more obscure indie titles, the best place to go is still your Windows PC. (And you can plug your PC into your big screen TV and break out a wireless controller if you still want that console experience.)
Since the more successful OUYA titles are already available on more mainstream platforms (or soon will be) there's not really a compelling reason to rush out and pick up an OUYA at this point. This may change in the future; more games are coming out on the OUYA all the time, and it's possible that we'll start to see some high-quality, OUYA-exclusive games. But for right now, unless you're really interesting in supporting the platform, youre better off getting your fix for cheap games and/or indie games elsewhere.