We walked down the beach to here from the Mykonos Grand and the restaurant was very pleasant.
All of the restaurants in Agios Ioannis are priced middle of the road, not cheap but certainly lower than most decent places in Mykonos Town.
We didn't reserve a table, just walked in, and were still offered a very nice table right at the front overlooking the beach and sea.
The food was mostly very good, the sardines to start were excellent and my pork steak as a main very interesting and well cooked. My other halfs pork tenderloin was a bit dry but not enough to send back.
The beer came in frozen glasses and the service was pretty attentive given some groups came in so all good there.
If ever back in Mykonos I would eat here again, certainly better food than the much louder Hippie Fish next door.