The game has been playable since about 1am PDT until the last few hours because they are fixing some critical issues.
Idk where your playing but since launch I've been able to play exactly 4 hours. Two of them of which were spent repeating all of act one because for some reason my quest line is reset....
Couldn't get on until 3am Eastern time, played til 6am Eastern ... and I'll be generous and say I've gotten an hour of play time since 11am when I logged back in. Where are you that your playing since 1am last night?