I tried the bamboo but could not get used to it and returned it to Amazon. I use the mouse pad on my laptop to do the touch-up on portraits. But there's a trick to making that work - if you want to draw a straight line, you click on one end, then hold the shift button down while moving to the 2nd point. shift-Left click at the 2nd point to get a straight line.
To do a smooth curve, make it as a series of short shift-Left click points. This comes out a lot better than freehand, and if you don't like a segment you can Control-Z to undo then re-do it.
Also with erasing the background, use the lasso tool. Click the starting point, then move the mouse and click again, then again, ... until you've surrounded the part you want to erase. Move the mouse around to close the lasso (click on the starting point) then hit Delete. For a portrait I usually start where the image touches the left edge of the frame then work right and up until I'm at the top of head, then straight up out of the frame, left, down, and close the lasso. Then Delete will clear the upper-left section of the image. Similar for the upper-right section to get to just the face (or whatever I'm rendering).