I was surprised and shocked to see the variety of reviews - especially the bad ones - for this place. I have to say that our experience there was entirely positive.
First, as another reviewer has mentioned, this is no Holiday Inn. My suggestion if you want Holiday Inn is don't go to Monemvasia, it's not that kind of place. Ardamis is a beautifully restored historic building in an amazingly atmospheric historic town. It is located just inside the walls of the lower town, quite close to the only entrance. You have to negotiate some fairly steep steps to get there, but that is true of almost everywhere in Monemvasia. If you're reasonably fit it should not be a problem. The welcome from the owners was extremely friendly (and the welcome drink very welcome!).
We chose to stay in Double Room No 15. The room itself is simple and nice. It was spotlessly clean (except for a little verdigris on the antique bathroom fittings, which did not bother us at all). The bed was very comfortable, the refrigerator, TV and airconditioning all worked. The lighting is very good, though it took a while to figure out the profusion of switches and dimmers.
For me even better than the room itself is what is outside it. The front door opens on to a small open patio followed by a patch of grass, with a table, chairs and a few trees providing shade. Immediately in front of that is the (public) path around the inside of the city walls, from which there is a vertical drop of about 10m down to the sea. A door at the back of the room opens to an inner courtyard, with tables and chairs and all-day shade (this is shared with a couple of other rooms). So there are plenty of places to sit and relax and recover from the energetic process of exploring the town and castle.
Since we often recommend places we have stayed to friends, we asked if we could see some of the other rooms, and were shown some that happened to be unoccupied at the time. Every room seems to have a different architecture and atmosphere; all the ones we saw were very nice. One even has an 800 year old well in the middle of the sitting room, beautifully illuminated and very impressive, though not much practical use. Another (which we didn't see) apparently has its own private hamam (Turkish bath).
Behind the reception is a large veranda for common use, with an incredible 360 degree view: in front the sea and the Peloponnese coast; at the back the huge rock with the castle ruins on top; and all around the buildings of the lower town. The only problem is there is no shade, which effectively restricts its use to early morning and late afternoon/evening. Apparently this is because the authorities do not permit umbrellas as they would spoil the historic views - a rule I would fully support.
Overall, if we ever return to Monemvasia we will definitely choose to stay at Ardamis again, and probably in room 15.