Already having a great reputation, Blizzard just abused their customers trust and realeased a half finished, repetitive, short, unbalanced, simplified game that won them a ton of money. The instability of the service was not a mistake. They knew that after a few weeks at least half of the players will stop playing and an investment in servers would have been a waste. So, by this time they did not optimize anything. It's just that people stopped playing so much.
Updates ? Read the change log latelly ? How is this good design ? In SC2 updates fine tune the experience, while in D3 they change important aspects like CRAFT COSTS, DROP RATES and GAME LOGIC!!! Released when it's ready ? It's still not ready, and it has already been realeased. Now we just have to lower all monster health and damage for acts 2,3,4 on Inferno, add more items and lower craft cost so people don't get too frustrated.
Another Issues is the "NOT REALLY DRM", DRM protection. They wanted "pay us money for stuff" functionality, and to ensure that people don't hack the game offline and make uber items, they moved items, location, drop rates, spawn locations and drop logic to the server. So because they wanted auction house they had to move most of the SINGLE PLAYER GAME to an ONLINE format. F**K YOU GAMERS AND GIVE US SOME CASH!
Then, there is Bioware. They also realeased the 3rd installment of a game, that was criticised, especially for day 1 DLC (which was an actuall add-on to the story and could be skipped/not bought). The game itself is a master piece, that has offline single player and online multyplayer, as it should. Then they realeased two free DLC's, then they listened to people's opinion and explained the ending. How is this possible ? Stuck under the umbrella of EA, the most despised publisher ever, they still gave free stuff and wanted fans to be happier about their purchase. So they invested some man hours/money for the satisfaction of their customers ? I can hardly believe it!
In conclusion I will always buy Bioware games. They might not be perfect, in fact they will probably have their flaws but considering the previous experiences they will be great games, with a great story, lenghty gameplay, a lot of details and (most of all) a dedicated developer that cares about fans. On the other hand Blizzard has fooled me for the last time with their nice cinematics. When they launch something I will wait for realease, review and critique then I will consider buying a Blizzard game when pricess go down.
PS: Six months of just watching, and the first thing I write is a rant...