Firstly, here are useful links from the related forum and news threads on updating and setting up a Steam Controller in 2024 (or later):

1. The official dedicated updater.
   
2. The needed redistributable for said updater to work.
   
3. Of which you need the x86 version specifically.
   
4. And the support page explaining the new firmware controls.

Continuing with the review, or more accurately a re-post from a short showcase I shared on Discord:
On initial impressions, I really don't get how the Steam Controller got a reputation for feeling cheap, it feels like a quality and solid plastic thing to me.

Testing it, I did quickly noticed that as a game controller, it honestly sucks, especially compared to the Deck, which has better and just good inputs all around.
But that is fine, as instead I consider it the second-best thumb-operated trackball money can buy.
The best one being strapped to the Steam Deck (though finger-operated ones get better), which in turn I consider the best tablet for me.

Making for a great remote for leaning back at my desktop, especially with the duel-trackpad typing.
Which after passing the learning curve I consider the second best touch based keyboard, second to Steam Deck again.
As is apparent now that I really like Valve's controller design, hoping for a Steam Controller 2 with the Deck's inputs eventually.

What wasn't as smooth was updating it's firmware to the Bluetooth switching version, as the option got removed from the Steam Client (and the button which shortly appeared did not work for me, though this is on the not officially supported Arch Linux package).
It took a zip downloaded from a Valve employer's forum post and a specific x86 redistibutable, ran on my brother's Windows laptop to update it.
And even this script took a while and was less polished than 8BitDo's updater, which I ran later.

This controller will continue to see a lot of use from me, though I do now understand the viewpoint of it having failed as hardware from this video essay more.
That being a very interesting and fun short video essay worth a watch, or re-watch.

Bought years ago alongside my Steam Link. I still come back to Steam controller for FPS games despite it's flaws
If Valve ever made a Steam Controller 2 I'd buy it in a heartbeat

Dead on arrival.