Each ball has Bowling Buck bonuses. The more bonuses the higher the star rating. The higher the Star rating the better the ball and the more Bowling Bucks you earn with each game played.
Let's Bowl 2 is a 3D game when you swipe up to bowl be sure to swipe towards the pins. If your ball is off to the side and you swipe straight up you'll end up in the gutter.
The power of your roll is determined by how fast you swipe up. The faster your swipe the faster the ball rolls. If you swipe too fast you'll get a wild roll.