As soon as the servers came back up I went and did the Act 3 boss. That was a bit of a disappointment. My strategy was as follows: hold left mouse button over boss, when low on health, click one of four healing buttons. Done. Ok, on to Act 4 then. A little on the short side, but quite a nice level I thought. Then comes the boss. Same strategy = down first time. A bit of an anti-climax if I'm honest. Meh, I guess that could do with an adjustment.
First steps on the next difficulty have been a bit better. Nothing's really that difficult so far, but even the basic mobs have significantly more health and it makes the combat a bit meatier.