Spaceships are cool, and exponentially larger spaceships are (arguably) exponentially cooler!
HOWEVER, the difficulty curve also feels exponential (at least to me). The difference in firepower quickly becomes discouraging (i.e. Level 1 enemy has multiple homing fast turrets but the player only has 2 slow guns and can only fire at line of sight) Even if passing a level by pure luck, having no saving points would reset my progress in the blink of an eye.