For the console version, there is no sign-on to Blizzard servers for DRM protection. The usability of the console version is so much greater than what is reported for the PC one.
The similarity to the classic four-player arcade game Gauntlet has to be stated because for the most part you're simply fighting a crapload of enemies. Like every 10m or in every unvisited spot on the map there are enemies waiting to come at you. Loot, gold, and health potions are gathered along the way and they give you some motivation to continue the grind. The repetition can't be understated and when playing solo this can be a lonely and anxious experience. Minding your skills and inventory are the only breaks from the monotony. The good thing is that like in other RPGs the more you acquire and process the better you become so the fights should get quite interesting later on.
I've played a few fantasy action RPGs recently so I think I can rank them according to fun: The most fun by far is Dragon's Crown. Its adventures last only 10 minutes and the co-op matchmaking is seamless; In the middle is Diablo III because the action is rapid but it also feels like an accomplishment to finally reach a goal, though the isometric perspective looks old-school and uninteresting; And at the end is Dragon's Dogma, which is a shame because it really could have been the best. But DD has so much promise at the beginning and yet it becomes punishing and unrewarding to the point where it's no longer fun to play.
At the time of this review I have only invested a couple of hours in Diablo III, or half of the first act, but I believe I have a sense of the game style.