As far as bouncing the ball around :
Spoiler (highlight to read):
I used one combination to get the ball to hit a portallable surface, put the other portal in the small room and then used the cube to direct the ball once in the room. Didn't have to worry about any of the other combinations then.
I quite liked the moving platform section. Bit of a pain when one moves and your portal disappears but quicksaves can alleviate most of the damage there.
Spoiler (highlight to read):
I used one combination to get the ball to hit a portallable surface, put the other portal in the small room and then used the cube to direct the ball once in the room. Didn't have to worry about any of the other combinations then.
I quite liked the moving platform section. Bit of a pain when one moves and your portal disappears but quicksaves can alleviate most of the damage there.