I typically think of Photoshop as the ocean. Depending on where you use it, you can get really good at 1% or maybe 3%, but its so deep and so wide and the potential applications of it so vast that no one, not even the programmers, will know it all. Learn to do what you want with it and move on.
I still prefer real paper, with real ink and then scanning and moving on to the final version. There is a pressure/texture feeling that the tablets can't mimic, and i think of it as the ultimate level of "undo". Should all else fail, harddrive wise, there is still the original art!