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.
Well it will be fine even if you only leave it charging a tiny fraction of the times you use it. And with AAs you have to remember to change them anyway or it will die while you’re playing.
And if you think the process of:
opening the back cover, taking out the AAs (especially on the original steam controller), putting them in a charger, and putting new ones back in the controller
is even close to as easy as just setting the controller down on a magnetic charger, I don’t know what to tell you.
You’re not considering the scenario of a dead battery.