I've never seen sales figures of the shield, so I don't really know if it's a success or not. Better be after 10 years.
Still, it's one of the best streaming devices ever, most of its competitors are either dead or have been replaced with newer models. Even today, most streaming devices can't match it.
It failed as a gaming console, nvidia's initial push for android tv games fell quickly (there were ports of Doom 3, portal and Jedi knight among others), I think nvidia tried to push it for like a year or so. Still, it's an awesome emulation console running everything under PS2.
I've owned it for like 9 years now. Both controller and remote no longer work because of dead batteries (if anyone knows where to get a replacement battery, please let me know). It has outlasted 3 Smart TVs, actually my wife took years to realize the shield was doing the streaming instead of the smart TV.