Try the Arena. It's AI, and it's constructed, but it gave me the opportunity to ease my way into the game.
I felt pretty unenthusiastic and regretful of my pledge, too, though mine was largely tied to being overwhelmed by a second card set being introduced before I felt the game was playable (I played about five minutes of the alpha and didn't think the beta was ready for prime time when I occasionally checked it out). But I gave the Arena a shot when Armies of Myth was released, and it was just the introduction I needed.
Was Pro Player a bad idea in hindsight? Given my schedule, probably. But I think the game is coming along nicely, and the three packs a week forever is nothing to sneeze at.