Sleep easy is a good place if you are planning a budget trip. It is close to the center of Athens, maybe 5 min walk to Monstraki but the area is a bit smelly and dirty due to its proximity to the local spice and meat market. There is no noise at night but some of the walls are cupboards and you cant help to hear people making love next to you.
I spent two days first but then I extended because it was a perfect considering my budget and its closeness plus its safety. I have not seen anything weird around the neighbourhood during my stay.
the owner is friendly and is always available if you wanted to talk to him over the phone. Over all I can recommend it to budget trip and solo travellers.