Good hotel although would not recommend it if you are planning on using the metro or are a solo traveler. The way over from the closest metro station is insanely steep, and you need to climb stairs on an iffy block which gave us the creeps a bit.
While the rooftop does have an amazing view of the Acropolis, the terrace itself is pretty lousy, with old rusty tables and chairs and zero shade. All in all, I would say a fair hotel but I have stayed at better in Athens before....