personally, i thought it was quite good. the set function allowed for solo players like myself to run through, but still provide a challenge. i played shadowfury, and i have just a few bugs/problems with him -
i never saw his passive ability which damages the enemy activate, but maybe i was looking for the wrong thing?
metamorphosis made it very easy to regain 500 health, just activate and wait - perhaps remove the health when you transform back to make it more double-edged?