This game would have been grate, if released about 4 years earlier.
I have pretty good PC, which I bought to play the latest games. I love shinny new shaders, high res textures all on a HD resolution, possibly on a big screen TV. Reading the specs of this game, I find that I could have bought a computer for 25% the price of mine and still be able to play this game on max graphics settings. Make no mistake, this is not because Blizzard did a good job at optimizing the game, but rather because the graphics is extremely outdated.
The game play isn't bad, though I had a minor stroke when I saw how static the quick-bar was, and that I can have only one spell/category on it, this meant that even though I loved some spells, using them became impractical because I needed another spell in that slot. Additionally, it's disappointing that Blizzard didn't really do anything new or exciting.
The story is another thing that is outdated, it is a grate story for a game of 2007, but in 2012 we expect more. I think a 10 year old could have written it better. The main problem I had in this department was the fact I literally saw every major plot point coming from a mile away, from the identity of the fallen star, the the identity of Belial, and the betrayal at the end. In other words the story failed to keep me interested, there was no sensation of "I wonder what's going to happen next?".
Moving on to the always online policy that Blizzard took, I think we can all see it for what it is: a DRM system, a very good one at that. The one problem is the fact that users(me included) DO NOT LIKE IT! Blizzard isn't the first company to gamble on such a DRM system, and in the past such systems have failed even at achieving there first goal, stopping piracy. At some point a crack or an emulator will appear, and the only thing Blizzard will have achieved will be the fact that they pissed of a lot of paying customers.
You might be asking If I think that the game is so horrible, why the heck did I play it to the bitter end, the answer is: the loot and the progression. Even though Diablo III has failed on so many levels, the game is extremely well balanced, failing at keeping you interested with the story, but keeping your hand on the mouse with the constant flow of loot and challenges.
All in all Diablo III was a descent enough experience, but one I would not pay for given a second chance.