I meant more that they're very unbalanced. As one commenter noted you can get a crazily good railgun very early and be invincible. Equally you can pick up a weapon with random aiming and then have a very very hard time progressing at all.
On my second try, I got a double (Forward + backwards) railgun early on. So overpowered it's not even funny. Most enemies don't even make it out of spawn zones, if you take a hit it's a sign you're falling asleep.
Tip: Don't choose the acid weapon given the choice, it's really bad.