I found the controls counter-intuitive, but the core idea is so solid and I love how the baddies exploit the different parts of the combat system - very clever design for the enemies.
I wish the controls had been tighter, because this is very skill testing and I don't like having the option to blame the controls instead of my skill :)
Also the powerup selection was a little frustrating. I'd hop on an archer and they'd be the last enemy in the wave and instead of getting the health I'd desperately need I'd get +100 points. I like how you tried to integrate the power-up selection into the primary game loop, but I didn't like when I accidently didn't get what I wanted.
Overall cool concept that feels like the core of a good, fun, arcade game.