Got it yesterday and took off an hour early from work only to get home and install and find the servers down. Wow (not World of Warcraft). So ate some supper, and gave it another go. It plays great on my Mac Pro (2008 8 core, ATI 4870, RAID0 SATA2s, 8G ram) so I believe an super gaming rig is not really needed. Did some co-op with a guy from work, for the rest of the evening and it was fine till about 9:30pm, then LAG deaths started happening to me.
I am VERY disappointed in the always connected server side content for single player. I can handle a connect for verification, but not for content, as my internet is flaky. I may play
through the game, but it will prevent me from becoming an addicted DIII player.