Obviously, there is nothing to add. 20 euro per night is a good price, especially, when the hotel is in the city center. For me it was a base for city trip, so I've arrived there at night. Omonia square is famous to be dangerous at night, and I've experienced evil looks from homeless, drug addicts, simply drunk and street thiefs.
Hotel is fine - you can come 24 hours a day. Room is small, but rather clean. It is little noisy outside, but not dramatically.