It's not difficult; getting a strike involves a single timed button press. (dreamandfriends.com)
The game has three difficulty modes, easy, normal and hard; depending on the mode picked, the speed and required amount of button presses increases as you advance. (miketendo64.com)
It's well designed so that the taps generally come in groups, rather than mixing in with button presses. (playstationlifestyle.net)