I generally like the gameplay, the enemies AI, especially big guys is something pretty cool. The spritework is pretty good as well, though I"m not the fan of blurred background honestly, but it looks alright and does it job.
The stamina management seems broken: if you get damaged and lose to much of it, even respawning does nothing, you're just stuck there with no abilities to use.
I'm not sure if the game uses the theme. I've managed to get up to the level with 3 big dudes and a couple of small ones, but haven't seen any keys so far.