PAP is a good platform to start with, although a trial version of Toon Boom Studio would be more ideal. I’m not promoting TB per se (I use Digital Pro professionally and love the workflow and “faux” 3D effects), but the price of TB Studio (v4-4.5) has dropped to more “affordable” levels. Much of the 2D content out today (Family Guy, much of the Adult Swim catalog, etc.) uses Toon Boom in conjunction with Max/Maya.
Regardless of the software, be prepared for a steeper learning curve if you’re not familiar with rigging and keyframing, though. It helps to have some experience, whether in Flash or the “old-school” method of cell/plate animation. Also, you’ll be more prepared to move into 3D animation, if that is another possible area of interest.