I liked the big friend/small friend dynamic, and the sound for reloading being in rythm with the music was a really good touch!
The arena graphical design could be a bit smoothed out, as would be the number of monsters in later waves (wave 15 was big big barrage of those magic people, and were a bit tediuous to take out), howver, the character design is really good looking, and with the music makes it really easy to want to reach the end of this game :)