I have beaten it with Rogue - a couple of tips:
a) Whatever class your are playing confuse will help you a lot if you can get it
b) Don't try to clear everything - some places are just to dangerous for some classes
c) Rogue strategy sleep -> crit -> run works really well
d) Charge and Power strike are very useful for Rogue
e) Dungeon senses help a lot when you fall into next level
Good luck people!
I like this game very much, but there are some bugs:
1. I had -6 population and still was alive
2. When I had 36 population, 93 villagers volunteered for the Kingdom's Army
3. My gold was disappearing without any reason
4. I am able to attack myself (?)
5. After Orcs raided me, my heroes were killed? Because they disappeared.
6. I accidentally changed my cities, this system should be clearer.
But keep improving it, it has the potential :)