The thing about hack 'n slash dungeon crawlers is that the combat needs to be astoundingly excellent. Since the combat is 99% of your activity, it needs to feel right. Games like Dragon Age or even Baldur's Gate have you infatuated with the world, your party setup, character building & role-playing & you role in the world. 
 
Your goal for games like Diablo & other action rpg's is: Kill everything! 
 
But even then the formula is hit or miss. The thing I think is important is this: Overkill! Since the only thing you are doing is slaying monsters, you need some sensory overload accompanying this. I remember that in Diablo 2 we had Druids running around whilst being the center of a Maelstrom, Sorceress' would 25 lightning bolts as fast as you could click. Same goes for the Amazon firing 15 arrows at the same time, or the Barbarian whirl-winding across the screen tearing up everything in sight.  
 
Thats the kind of overkill that I generally miss from other Diablo-like games. They lack that excitement. 
 
Having said that, it looks as if Diablo 3 is shaping up to be exactly what I just described. (See the runes explanation here: http://eu.blizzard.com/diablo3/world/systems/runestones.xml) 
 
I am stoked!