I quite liked it. The frantic managing of items, decisions on which units to make, and tactical unit placement made for quite a challenge!
Managed to get to wave 13. Do comment back if someone beats me, I will try again to get #1 ;). However, I'm still a bit confused about how the red / blue shields on the monsters work. It feels like half the time the blue shield blocks ranged attacks, and the other half it doesn't block them..? Usually I put 2 units next to them just to be safe