If you keep hitting A it will give you a free 5-6 hit combo, and if you have at least 50sp when you do it, the game will automatically cancel the last hit into a super. You can do all kinds of long impressive combos but due to damage scaling it really is not worth trying since the mash A combos are so damn effective.
I think the mash A function should have been optional for beginners. But since it is a regular part of the game, it really makes me not care about the title that much. I prefer a game like Guilty Gear where more skill is required.