I think smaller gamepad controllers are not as good as a full size controller with more buttons, longer battery life, and features.
Smaller controllers also look uncomfortable to use for long periods of time.
But, they can be good for gaming with if you don't have enough money to buy a better...
Since the first sale of the Wii U, the only way to get a gamepad was to buy the whole console set up. Now Nintendo is selling the Gamepad by itself for 12,800 yen, which roughly converts to around $104 USD or £70.
Still, no game makes use of a second gamepad which the hardware is region locked.