The hotel staff are great, speaking several languages. The pool is small, but never got crowded during our stay. The hotel is roughly 10 minutes from Fira and 30 minutes from Oia by quad bike. There is a scooter/quad bike rental store just down the street from which we got a quad for €120 for five days, the lowest powered scooter would be about 60 I think and they have a whole range of more powerful ones. Messaria contains a medium sized supermarket and some smaller minimarts which are open late, there's also a wonderful family run taverna a little way after the scooter rental, they had a better Greek salad or souvlaki than anywhere else that we went to, including some very pricey places in Oia and the service was by far the best that we experienced.
As for the negatives, the wifi signal is weak in the rooms, we went to the foyer or the patio, which was perfectly fine for us, but it was almost unusable in the room. The shower is very small and the curtain couldn't keep the water in unless we were very careful. The TV has five or so Greek language channels, there's nothing in English. These things were minor though, for such a cheap hotel we weren't expecting much beyond the basics, and they delivered that along with lovely service and great recommendations. There may be better places, but if on a budget, you can't go wrong with Hotel Kalisperis.