For a dormitory, I think it's great.
But for those not familiar with it like me, just be aware of a few points.
Whenever your roommates move, go to the bathroom, shower, go to bed later than you or wake up earlier, all of it wakes you up.
It was 38 degrees outside when I stayed but for some reason the air-conditioning wasn't working well so it was really hot for sleeping.
Lockers are at the reception, cost 2 euro and once you lock & reopen, the money is gone.
But for 18 euro a night, in central Athens in a safe neighborhood, it's good.