Based on the description on their site, the controller includes a built-in battery: "8.39 Wh Li-ion battery, 35+ hours of gameplay... "
That was disappointing for me. Specially condidering the Steam Frame's controllers make use of AA batteries: "One replaceable AA battery per controller, 40hr battery life"
AA Batteries might not be as convenient to use, but being able to replace them is a great advantage. All my Xbox360 controllers still work fine, but none of my PS3' Dualshock 3s.
The official docking station could be used to recharge (rechargables) AA batteries so the functionality could remain the same.
Huh? Rechargeable AA and AAA batteries and chargers are highly affordable and work great. I only have a few items where I don't use them like smoke alarms. For everything else I use rechargable and absolutely love having devices with easily swappable batteries.
Yeah but most people don't buy them. If you release a product that uses aa batteries most people are going to buy disposable ones and most of them will not dispose of them properly and just throw them in the trash. Some people using rechargeable AA batteries is nice but it's better to just remove the option for disposable batteries and make it with a builtin rechargeable battery.