The ball bounce feels very random
#Recommendations 2D mobile tennis game
jagged island
shell birch
The changes in ball size also looks bit weird. I'd simulate the ball movement in 3D and use the height to figure out the correct scale at any given moment. I don't mean you need 3D physics although you could use them
shell birch
Actually why not even use a perspective camera to do the scaling for you automatically. It would still look as 2D as it does now but the distance to the camera would define the scale of the ball