At this point, the controller is the most exciting thing for me.
Steam machine is cool, but with how good handheld PCs already are, I'd be ok spending a bit more and just using those instead and docking it for TV gaming.
Steam Controller was significantly better than Xbox controllers for some kinds of games, but it was much clunkier for others. Steam Deck's controller is an improvement over either of them, and this new Steam Controller appears to be pretty much Deck's controller without the Deck, with some tiny extras added.
The Steam Controller is amazing for first person games. I set the right pad to quick mouse movement with some inertia and the gyro to precise mouse movement, and it feels so natural and pleasant to use.
I have six of the previous generation controller and I love them, only minor annoyance is pairing them occasionally. I don't really use the haptics part all that much though
idk about that - integrated buttons, battery, screen, size constraints and the R&D work that goes into all of that is probably significant compared to 'box with hardware and usb ports' (oversimplifying to make a point here though - of course lots of design work went into this as well).
Steam machine is cool, but with how good handheld PCs already are, I'd be ok spending a bit more and just using those instead and docking it for TV gaming.