Fantastic!
I don't know why they say that it's to hard... I didn't die once and my castle wasn't hit, you just need to manage your skills effectively! And a tip, before the round starts(RIGHT before!), use Fire Wall at the enemy entrance. In the beginning, all enemies will die( maybe 2 will live) and in higher levels it takes care of (most) mages. I have nothing to say except that a stat system would indeed sound good.