This hotel's main selling points are its location and its prices.
There are few hotels in this area of Athens, which was completely overhauled for the 2004 Olympic games, and turned into a relatively trendy semi-pedestrian area. The many large coffee shops and their outdoor tables are very popular with locals in warmer months, but upscale enough not to become boisterous.
At one end of the long road is a subway station with connections to both Piraeus and the airport, making it the ideal stopover before/after a visit to the Greek islands. At the other end is the Acropolis. Being able to visit Athens without using taxis or walking through major roads is a boon.
The hotel itself is nothing spectacular, with somewhat tired rooms and obsolete bathrooms, but given the price and location I have no complaints. I do remember from a previous stay that the air conditioning struggled in the summer.

My son and I stayed at the Hotel Phidias for a couple of nights in late May while visiting the sites of Athens. The location was great. We walked to the Acropolis, the Agora, the Plaka, the Temple of Zeus, the Philopappos Hill, and the Roman Forum. The hotel is right on the pedestrian walkway which encircles the Acropolis and Agora, and a variety of great restaurants are nearby.
The hotel room we had was not very good. The bed was not comfortable and the pillows very lumpy. The room was dated and somewhat small. We had issues with the small shower leaking with each use.
The breakfast was terrible. Everywhere we stayed in Turkey in Greece had great breakfasts with fresh fruit, cheeses, and cereal. The Phidias breakfast was bread, jelly in packets, cheese slices in the wrapper, and cocoa puff cereal. The coffee was good.
If we had to do it over again, we would have spent a little more and stayed at a hotel in the Plaka area.

Overall this hotel was pretty good. The location is in a super touristy area of Athens. The street that it is on is lined with nothing but cafes that overcharge for dinner and drinks (although just a few streets away are some really amazing, well priced restaurants). There are peddlers everywhere on that street as well as a flea market on Sundays selling mostly fake designer purses. Some staff members are very friendly, and some couldn't care less about you. The rooms are outdated but decently sized and clean. One of our rooms had a balcony and the other just had a sliding glass door with a railing. Breakfast was pretty dismal with only bread and cheese and some cereal. It is close to the Acropolis, which is a huge plus. No WIFI although Athens has a free wifi that we were able to pick up in the hotel with a computer, but not our cell phones.

This hotel is definitely a 2-star hotel, but it would rank as one of the best 2-star hotels I've stayed at. So, you get good value for your money.

PROS:
-free breakfast (toast, cereal, cookies, tea, coffee)
-near attractions (across from Ancient Agora; can see the Acropolis lit up at night from front of hotel. Gorgeous!)
-near a metro stop
-on a pedestrians-only street
-room had a very large closet which helped get stuff out of the way in the small space
-friendly, helpful staff (especially Vasilis)
-lots of nightlife nearby although noise level is reasonable
-room-darkening curtains
-extra pillows available
-good-sized shower; worked well

CONS:
-Bed was in poor shape: worn out in the middle
-Decor was outdated
-Toilet worked but was a bit tricky to get it to flush
-no fridge in room
-milk for cereal was always hot! (I guess for the coffee)
-shower was hose only; couldn't hang the nozzle

NOTES:
-It wasn't hot when we stayed here, so I'm not sure how well the air conditioning works