I have an original Steam Controller as well. The Steam Deck is a lot better in my opinion because I can choose between thumbstick or thumbpad on each side, whereas with the old controller you have to live with the touchpads and the single stick on the right.

The build quality feels a bit better too, and the haptics a bit more refined.

Really, the Deck offers everything the Controller did aside from form factor. And maybe if some folks vastly prefer the bigger touchpads, that might possibly be a downside, but I doubt that’d be the case for most