I too expected that the crank would charge the device. Nope.
I also saw the name, Playdate, and automatically assumed the device could connect via Wi-Fi or Bluetooth to other Playdates nearby to create a cool little on-the-fly multiplayer gaming environment. Nope.
So basically this is a tiny black & white Gameboy with slightly better resolution, wonky controls and a subscription-based game library of indie/experimental games that will fit both the little screen and the wonky controls. For $150.
It also reminds me a lot of this for whatever reason: