Thanks for the feedback on the controls. I changed the control schema couple times during the jam and there's a commented out code for the WASD/Gamepad :)
This will be added in the next version.
As for the speed of the bubble I actually wonder what would people prefer:
a) movement speed depends on the size of the bubble.
b) movement can be speeded up by player (maybe additional control or mechanic similar to angry birds)
c) movement should be natural unless affected by the environment (e.g. wind).
I would really appreciate your thoughts on this.