I've been using a Wacom tablet for 10 years now (almost exactly 10!) I use mine for everything. I have an "up-down-right-left" mental problem with using a mouse or track ball, that disappears completely when using a pen. With a mouse, I often can't figure out where my cursor is. With a pen, I know exactly where it is. So, I use my pen for everything.
The reason I got one in the first place was to use with Painter. I had to switch from "real" art products because they were making me sick, to "graphic" art ... and Painter was what was the best at the time. I "draw" and "paint" with my pen.
I got so used to the pen, that I use it as a mouse. With my newest tablet, I am finding that I use the mouse a little bit, but I had to turn off the side buttons because I kept pressing them by accident.
At this point, I don't know if I could use a mouse all the time ... but I don't plan on trying.
Tandika