What is a successful delivery? I guess that depends. I would say a successful delivery is releasing the product. Given they've got a very aggresive schedule and are promising delivery for September 2012, I'd say a successful delivery would be getting the product out to backers before the end of the year (ie, the holidays).
I do think they are setting themselves up for some serious pain - it's very difficult to turn down money. I think originally Ouya had a 5,000 limit on the $99 reward. Now they are offering 80,000, and the estimated delivery date hasn't changed. If their delivery was to slip (not all that surprising) the number of vocal angry customers who maybe don't fully understand the nature of Kickstarter funding is going to be much greater.
Good luck to them - but it's important to go into this sort of thing with some sense of proportion. Even the best intended and funded projects can and do go a bit awry on the way to delivery. Just look at the team behind Ouya - their designer, Yves Behar, is a talented man, but two of his most well known projects (OLPC and the Jawbone Up) had significant delivery issues.
