The hit box is simple too damn large to have high health bullet spam enemies be as common as they are. First it is the purple dual shooters, then the blue eyes. When they come in swarms of 10, as they almost always do, they fill the screen with so many bullets, it is literally impossible to dodge them all no matter what weapon you are using.
If you use the flamethrower to try and take them out quickly, you are killed nearly instantly by the ridiculous damage output a swarm of them puts out. Try to play it safe with the basic gun, and you can't even kill half of them with a damage focused build before they start rushing the ship. And lets not even pretend skill are an actual option with swarms, as if with the pitiful damage all skill but the grenade do were worth their mana and skill point cost, or that mana regen was anything but laughable even with the regen maxed to 11.
Speaking of skills, the only two actives worth anything are grenade and Berserk. The damage shield requires too much investment and is only useful if you still happen to have reasonably high health. The meteors to absolutely pitiful damage. The the homing missiles might have been nice if they ever did enough damage to kill something and didn't waste them selves of mine walls and tiny mooks. CoD is suicidal to use to use effectively and each bolt hits one target. Have not gotten to try WoF or MB as of yet, but they fact that they both cost more than 150 mana, making them impossible to spam cast in a pinch makes me highly suspect of their worth in comparison to a 3 grenade spam. Finally, limiting max mana to 300 was just an all around bad decision, in my opinion. The levels are too short for an infinite mana pool to be detrimental and limiting to 300 basically ensures grenade spamming to be better than pretty much any other option in almost all situations.
On a final note, the cost for equipment is insane. When I unlocked flamethrower, I was itching to try it. But the price to buy a pair of them to compare thier them at max effect to the first weapon was way beyond my means and resulted in damn near 30 minutes of grind... just to check an early game weapon out.