The three other weapons feel pretty useless compared to the main one, they are too slow for how hectic the game can get, I only used the boomerang to get rid of the shielded enemies.
The boomerang takes forever to come back when you are changing attack directions.
Shotgun seems utterly useless.
Weapon switching needs better feedback, it's hard to tell which weapon I'm currently equipped with except for the sniper which has its own graphics.
Some of the smaller enemies spawn outside the lanes which makes them harmless and pointless.
Very fun game though, the concept is solid and I could play it for a good while, I think the biggest issue is the weapon balance.