I'm not passing judgement on the OUYA controller's touchpad until I try out some games that use it but at first... I'm pessimistically optimistic. I realize that makes no sense but work with me here:
The touchpad is fairly small and non-visual. Mostly anything you do with the touchpad you could coneivably do with the analog stick and buttons. But who really cares? Even if the touchpad ends up being useless, it's taking up controller real-estate that would have otherwise been unused.
I'm eager to see how developers integrate the touchpad but I think it will be a huge challenge. If they don't succeed? Oh well, no big deal and no loss.
Told ya. Pessimistically optimistic.