The population bonus from the world should be scaled up. It gets pretty useless when I already have hundreds of thousands of trimps and I get just 5 from defeating a monster.
Put everything on DEX. It will give you a lot of attack speed. I defeated the last boss in about 3 minutes with the last damage of about 8000 (the damage increases as you hit your enemies).
5/5 Very good game.
I think it would be better if endless mode would be harder. I've played for about an hour but I can barely notice the difference in difficulty