I love it. The key is setting the triggers as the left and right clicks though. I find clicking the trackpad not great for precision. There is a certain level of tinkering/customizing that will be needed to get the most out of the controls.
I’ve played several 20 year old FPS games with absolutely no native controller support and completed them all. If you put in a little work in getting the controls how you like them it makes it hard to play stuff without all the Steam Deck options.