For me it’s comfortable. But obviously is less confortable then a controller (like dualsense or xbox controller) due to size and weight.
Usually if I have to play for a short time (or while I’m out) I use the steamdeck directly. However, if I have the opportunity to play for a while I prefer to connect a controller.
Yes, surely is worth.
But, if you know that 95% of the time you will use it in docked mode, shouldn’t you consider buying a better PC than the one you currently have?
It’s one thing if you need it because you want to play it in handheld mode, you have to travel, etc… but if you always keep it docked you’d probably be better off considering a PC.