when visitng my mate a few weeks ago we blasted through the entire game, took a few hours. He went through as the hunter style class (bow and arrows) I went with the barb.
It was intersting seeing the 2 different classes develop. At the start I had the edge, mowing threw mobs like a hot knife through butter, but slowed right up for a good few levels, had to really be careful as things destroyed me.
equally he started slowly, like a glas cannon, but like all glass cannons his damage soon became insane and mowed his way quickly down.
however the game ended with him having to fight the last boss for around 30mins. dieing over and over. He fought near the entrance so when he went into the main chamber after the fight there were nearly thousands of bodies from the spawns.
In comparison the barb munched through the fight in about 15 hits.
all in all, very fun game, but after completing it it doesnt tempt me to go back, could do with multiplayer. The extra dungeons aftyer you have completed the game are fun briefly but provide no challenge.