They actually made diablo 3 [Blizzard North], well had a near complete working version years ago, but scrapped it because it didn't meet the expectations of the parent company Vivendi. Blizzard north was apparently closed down because of this (You can find screen shots online). Some of the original diablo 1+2 guys ended up making torchlight. So yes diablo 3 has been in development for 10 years, but the version we got most likely only the last 4 years.
I totally agree with the above, there is no way this game could have been in actual development for more than a decade.
This was truly and for most part i think many will agree , the biggest let down for the one of the most anticipated games in gaming history.
Now i gave this game a fair chance, heck one could say i forced myself to play it to just find something that can justify the price i paid (Bought the CE) and give it some re playability.
I have 9 characters, 6 of which i play (one of each class and a hardcore WD)
The other 3 serve as pack mules.
I have a lvl 60 DH and Monk, working towards finishing inferno.
But it becomes an item grind for gold farming to spend in the AH at the end.
I read through the Patch previews for different classes on the web.
And I must say i very much like what im reading, but agree with this all things that should have been addressed in the previous patches already.
This won't save the game, nor would PVP.
Financially the game is a big success i mean come on, who ever would have thought Blizzard, a studio that sets industry standards with their games , would screw up one of their biggest franchises ?..so i kinda feel Blizzard scammed everyone..or for that fact the hype sure did.
But game wise it's a let down to the genre and fans everywhere.
The story is horrendously lame and predictable, the skills system suck! the lack of customization and own attribute assigning is another big issue.
To me it felt like a game from a 3rd party studio that hired Blizzard to do their cinematics..
I mean i played a bit on Sunday, and i kid you not, there were like 23 people in the General chatroom

I opened my game to the public, in the 3H or more that i played, not one ....not one single person joined.
This game will need a few expansions to rectify all the bad mistakes, if it is even repairable.
In short, people won't be so eager to hop on the hype wagon again and pre order the Expansions so quick.
Blizzard will defos need to give public beta access for all to demo the game beforehand.