I love hearing you say that, because a few people have said the exact opposite thing. :)
Did you find it super powerful right away or after upgrading it a bunch?
I like your idea about moving backwards being a bit slower. Next update will probably see some experimentation with sprinting for energy, so I might look into that as part of playing with the movement speed.
There will probably be more enemies that have some sort of shielding against arrows in the future. Spidertron 6000 won't go down in one shot for example!