The playtime is about 2 days and 6 hours. For the ones interested, here is a short list of the way I did it.

lvl 1-8 = grinding at the start spot
lvl 8-16 = Rage Fire Chasm
lvl 16-20 = Shadow Fang Keep
lvl 20-45 = Scarlet Monastary: Cathedral ( only )
lvl 45-( probably 58 ) = Startholme ( 3 quick pulls )
That's very impressive. O_O

But Cathedral at level 20? How do you do that? That seems highly ineffective if you ask me.. Doesn't everything get resisted? :S