Well, I had about 200 hours of gameplay on my account, farmed over 100m (and sold) Quit because everything worth playing for was nerfed, making inferno insanely hard. It was impossible to finish Inferno Act1-Act4 legit. Also, all the items were inflated, people had fancy items worth hundreds of mils but no one could afford. And to top that off, whenever blizzard blunders on D3 (quite often) the scenario where a D3 player must send in a support ticket and wait a week for a reply that has nothing to do with the ticket.
TL : DR
Blizzard is stupid
-First attempt at stopping bots came in late as hell, and ended up effecting everyone
-Nerf skills that were made classes desirable
-AIS nerf made a lot of people quit
-Drop rate (increase crap drops, lower good drops)
-Bosses drop sh*t now
-D3 could have been an amazing game, but blizzard fu*ked up.