Bought one last year, and I've probably put in 100-150 hours. Not playing it too much because I've had games on other systems be priorities, but I have loved it. Probably the best way to emulate the 16 bit and prior consoles, plus PS1 and PSP.
I have to say, the Visual Novels really do shine. Stuff like Killzone and Uncharted are super impressive and all, but it's just not a great experience playing those Games on something so small, and they don't really benefit from it. But stuff like RPGs and VNs conversely don't benefit much from being on a TV and are great for pickup and play sessions on a handheld. Recently played Mother and Danganronpa, and just started up Disgaea 3.