Not that good , because it doesn't allow the ship you purchased to be used on every wave or level along with the so called attachments, the so-called shield doesnt last linger than a blink of an eye, you waste couns on upgrading ships that still dont do great damage on level ups, regular game play doesnt allow you to maximize the ship power even after you get twenty or more "power ups"(more like power downs)! ETC... All those extra "power-ups" should be used to power up the weak 'wing-ships.'