I used left touchpad as a touch menu when I was using the left joystick. After moving to the left touchpad I prefer it over joystick due to being able to rely on a sprint hold mapping it on the outer edge without accidentally triggering it like I would on the joystick. And I’ve come to love mapping stuff like crouch, slide, or dash to it too so combining movement actions to touchpad clicks. Frees me to use back buttons for other stuff and further reduce my need to lift my thumbs away from movement and camera controls.
That’s my experience as left joystick and left touchpad user.
I use the Steam Controller still for games like Doom Eternal, Left 4 Dead 2, Spin Rhythm XD, The Finals, etc.
Basically any first or third person game that has aiming, but I am not sold on the Deck touchpads as primary inputs. Tried it and didn’t like it. Found them uncomfortable, size too small, and shape resulting in inconsistent swipes as someone who likes to target a consistent 180 on an edge to edge swipe.
So it will be a good controller for dual joystick users who occasionally want to use the touchpads, but not a good follow up to Steam Controller users who wanted a new controller to use the touchpads for a majority of their games.