I've never been a console/controller gamer, but I remember the first time I saw it - it was an early fake, that looked and felt very similar to the end product but inside it just had a metal weight and no actual electronics, and it seemed like such an exciting product, it was genuinely hard to keep that secret...
(And come to think of it, I think I misremembered when writing my last comment - I might be wrong, but I think the Alienware Alpha that launched with Windows actually shipped with an Xbox controller, and the steam controller was only available once the proper Steam Machine version was out. Not 100% sure, maybe we just needed the Xbox controllers for the press sessions before launch...)
It's the absolute worst controller I've ever used (Joy-Cons are a close second).
I didn't use it because I hated it so much, put it straight back in the box after a few days of trying to use it and eventually I sold it for as much as I paid, and I was glad to see the back of it.
The size/shape of the controller as a whole was fantastic but I just really hated only having touchpads instead of sticks, and that made it unusable.
Sticks work really well for me in terms of controllers, I just wish we weren't being shafted by stick drift all the time when manufacturers could be using hall-effect sticks; I've got 2 PS5 controllers and 3 PAIRS of Joy-Cons with drift, while I also have my original 2 x PS1 controllers from my childhood, neither of which has drift.
The best goddamn controllers ever made, too, I still have one in a box somewhere around here and I won't use it because it's so awesome I don't want it to break. Pretty dumb eh? The two touchpads were the absolute best, I've never had control like that in an FPS and to this day I can't play any FPS with a stick because I was ruined on the Steam Controller.