On a personal note, I started off with a mouse while doing computer artwork (all forms, not just maps). I got great results, and still can. Then I got a tablet, and while I can work without it quite effectively, I rarely use the mouse for *anything* anymore (unless i'm not at home, and using my brother-in-law's computer). The learning curve was insanely easy to overcome for me, I just played a few solitaire games and such for a weekend, plus puttered around in photoshop, and booyah.

Overall my review would be along the lines of "Need tablet, no. i can work fine without it. Want the tablet? Heck yes, I love using it and can do more than I thought with it."