To become a good ball handler you need to be able to control the basketball while you are dribbling. This wall tennis ball toss basketball dribbling drill is great for developing hand strength and ball control. The in and out move will help you develop the ball control that you need for in the game.
Also, these types of basketball drills are great for learning to dribble with your head up. It is important that you learn to dribble the basketball with your eyes up the more advanced of a player you become. This will allow you to see the floor, read the defense, and then ultimately help to make the correct play.