I don't think there were issues with the game, it just seems like network utilization is through the roof. Way, way more people connecting than anticipated, which isn't something you can quickly fix. You can't simple increase bandwidth and buy new equipment. Stuff like that takes a while to setup and configure, especially on new products, since theres no baseline to go off.
Its still frustrating as hell for the users though lol. I love the people who think they are going to be taking blizzard to court and sueing them, the forums really make you lose faith in the human race