The Adonis Hotel was a lifesaver for us on our recent trip to Greece. We had a horrible experience at the Tempi Hotel and ended up getting a room the night we called (4/1/07) and for the following Friday. I don't understand why the Adonis is rated unfavorably compared to the Tempi, because they're worlds apart. This may be because of the type of travelers staying at each one - the hostelling crowd may be able to better tolerate the Tempi, but a more discerning traveler might be disappointed at the Adonis. Anyway, our room was clean and had an adequate (not luxurious) double bed. My sense of Athens hotels is that for anything more than the barest of bare bones accomodations you're going to have to get out of the budget hotel category. Still, the Adonis staff were all very friendly and helpful for us: telling jokes and laughing at ours, calling the National Archeology Museum for us on Good Friday to check the hours. Breakfast was about the minimum you could get away with calling breakfast, but the view from the eating room was fantastic. So, in the end I think we got a good budget hotel deal in a great location, which is all we really ask for.

Hotel : Old, dirty - uncomforable
Location : situated in good location (close to Syntagma Sq.) - Convenient
Staff : unfriendly and not helpful - Bad attitude
Room : can't lock the door to balcony - unsafe
Rate : not suitable for budget traveller - average

We stayed at the Adonis for 2 nights before flying back from our trip to Greece:

Pros:
Central Location, walking distance to everything and in a safe area

Cons:
Super small bed,( hard) and paper thin sheets.
Towels are small and thin
As others have said, the shower stall is so small and everything gets wet.

It was clean, and we had a type of hadwood flooring which looked new. Unfortunately, room 103 was right above the staircase and we landed up hearing people check in and out all night, and then I was very tired when visitng the Acropolis the next day....

Wouldnt stay here again, I guess what do you want for 70Euro a night??

This hotel is so convienent and despite the impossibly small shower area (we rigged a better system for the curtain to some pipes up near the top of the toilet so the water wouldn't get the toilet all wet) we loved this hotel mostly for its cosiness and closeness to the Plaka.
No show on Greek yogurt was another disappointment but the breakfast breads/jams and juices were enough to get you going. I would definitely stay here again for the price vs. other higher end hotels in the same area. The price and location justifies any inconvienances. I would rather spend the xtra savings in the Plaka or the shops in Monistraki or on the islands for that matter. Btw, AC worked fine in early June. Be sure to have Euros to pay room in cash night before you leave....no CCs accepted.
One more thing, my daughter who is 20 actually like this hotel better vs. the Fresh Hotel we stayed at the end of our trip. She like the family-owned feeling of the place and loved how quickly she could hop over to the Plaka and explore the shops plus she felt very safe in the neighborhood at most any time of the night.
I would definitely stay here again and rig the shower curtain the same way to keep from going crazy with the water everywhere. Also, I did pack a small washcloth and would do so again...only one of 4 hotels I stayed at actually gave you a small washcloth to use and a few of these hotels were pretty pricey so I was surprised they still didn't provide for washcloths.
One more tip for the Adonis and other hotels (pricey or not) in Athens and on the islands....pack lavender spray to take care of bed bug problems. We did notice some bites in Athens and I got my lavender bottle out to spray around the bed and in/under the sheets...no problems after that or at any other hotel because I sprayed first. Apparently those nasty bed bugs don't like the smell of lavender!