Like the challenge; though I think the game might have been a bit more fun if the bosses were very slightly less beefy. Never quite got the story, unfortunately.
Hardest parts for me were the first boss (skeleton) and final boss. Some tips for the final boss:
* You can tell which attack he's going to use by the sound effects
* Try to stay in close as you dodge his attack and minions. This will result in enemies being clumped together a bit better so they can be killed more easily with melee or charge attacks. And help you keep the boss in range for consistent damage.
* Take appropriate evasive action of course.