It was a good choice for us. We stayed there 4 nights on September 2013.
The most significant advantage is the location: 2 minutes walk from Syntagma square, which has a metro station of the line that goes from the airport. So its convenient when you first arrive in Athens by air. And has 2 of Athens metro lines going via this station. Tram station is also nearby.
But it's also good for most of the important sights: took us about 15 minutes walk to reach the Acropolis, Acropolis Museum & Temple of Olympean Zeus; a bit less for the Roman Agora and Monastiraki; The Parliament (for change of the guards) is actually at Syntagma square itself, and the National Gardens are adjacent to it.
The area of the hotel felt very safe, and we had no trouble going around in the streets nearby, even late at night. Lots of restaurants in this area, and it is also near the main shopping streets.
Now, the room: Well, it was small - but most rooms at the center of major cities, at mid-range hotels aren't large. And it was very clean and well air-conditioned. the view wasn't much, but we had a bit of a view to the Acropolis (not much though, and had to be next to the window for that...).
Breakfast was standard - toasts, croissants, Yogurt, corn-flakes, etc. it didn't have much variety, but was very filling and tasty.
The staff: in the single case that we needed them, were very helpful - we had bus tickets that we ordered online, and it was written in Greek only. They helped us with it, called the Bus company to understand from which station it departs (there are 2 central bus stations in Athens) and advised on how to get there by public transport.
The only drawback was a bit noise of the elevator at night, but it didn't prevent us from having a good sleep after another great day at Athens.
I definitely recommend this hotel for this price category - it was a good choice, and even above expectations.