I feel the focus of II was lost in comparison to I. When you create challenges, you also have to make it so the challenges can be completed. Therefore, all of the gameplay must make allowances for this. When I played it, I found areas where I thought the game would have played out differently, had it not been for the challenges. I only played it through once though and will likely skip III if it has the same limitations. Still, you got my money BW, so you should be happy. I'll probably play III too, if the game is cheap enough. A low enough price will allow me to ignore the silliness of challenges.
It's been a long time since I played it, and it was enough of a irritant that I never replayed.