Proteas hotel is located in a safe and intereting neighborhood in Athens. It is around a 15 minute walk from Ambelokipi station heading West along Alexandros street . Many buses operate along Alexandros though I never used one to get to the hotel, which is located on a quiet street just to the South of this main thorough-fare. There are many conveniences close by (supermarkets, cafes, tavernas, restaurants, etc.). The hotel has five floors and a small elevator. Wifi is finicky in the rooms, but easy from the lobby. Staff are helpful and friendly. Room service for things like coffee is affordable and worth it.
The rooms are smallish, but both times I was there, they led onto a large private balcony on which you could easily host a small dance party (no kidding). The beds were comfortable (and matrimonial size), the room was clean, the bathrooms (no tub) were no frills, but once again clean, the air-conditioner was efficient and quiet. I think the hotel is listed as two stars, and it easily merits this rating. I've stayed in three star hotels which, though perhaps more elegantly decorated, didn't offer the same level of service and comfort.
A walk to the centre of town (Monastiriki, etc) takes around 20-25 minutes for young legs. Its an interesting walk which goes past the Academy, and certainly beats taking the subway. The National Archeological Museum is around 20 minutes away by foot in a different direction. The hotel offers quick access to Lykavittos Hill, a beautiful park which, if you're willing to climb to the summit, offers unparalleled views of the city. Being on the blue line, the hotel is also convenient for those going to and from the airport. All in all this was excellent value for what I paid: 55 euros in mid July. In all I stayed 6 nights here. I would definately return on a future trip to Athens.