Diablo III is an odd duck. It has that core hack and slash and gather loot premise that the first two games had and it is enjoyable game, but at the same time it doesn't hold a candle to its predecessors and really doesn't even feel like a Diablo game. The cartoony art direction that it inherited from World of Warcraft does it no favors, robbing the game of that grim and gloomy atmosphere that the series had in spades for the first two outings. Now it is more akin to Torchlight--a good game, as well, but something you play when you desperately need to fill that Diablo-shaped hole in your heart and can't get Diablo II to run on your computer.
The difficulty is weird, too. I remember playing the first two games and always needing a potion or several on hand for those many moments when things got out of hand and I found myself in over my head. This is not really the case for Diablo III. Once you level up a little and get some skills under your belt, you no longer need health potions. You rarely even need the health globules dropped when you defeat enemies. As I progressed through the game's Acts, I got curious about whether or not I actually took any damage in battle and started keeping a closer eye on my health bar. Sure enough, I rarely saw it diminished at all and it was always back to full in no time at all. Between the life-steal done by my weapons, the passive skills that gave me life whenever I did damage or used a certain skill, and the skills that straight up regenerated my health... there was nothing to fear. Even the big end-of-chapter bosses couldn't touch me; they just stood there, battering me to no avail, while I yawned my way through their giant health bars.
I boosted the difficulty up to hard when I friend decided to join me for the last chapter and battle with Diablo and it was the same thing, except occasionally my health bar almost fell to 3/4 full before immediately filling back up again and the bosses were even spongier.
Diablo III is an enjoyable game, sure, but much like all the other ARPGs that came after those first two games... you play it because you have a Diablo-shaped hole in your heart that needs filling. It can call itself Diablo all it wants, but it doesn't live up to the name.