Manolis' flat is in a great location in Fira. It's within easy walking distance of the bus station (all buses in Santorini seem to go via Fira), as well as the many restaurants etc.
The flat is really nicely furnished and modern, with two bathrooms and two balconies. Also has air conditioning in both rooms, which we didn't use, but I think would be very necessary in summer.
Communication with Manolis was good, always replied quickly to emails and allowed us to extend our booking by one day due to late departing flights. I didn't meet him in person, but he left good directions on where to find the keys.
Some of the pictures don't seem to match the accommodation we actually stayed in, but the flat actually seemed more modern than the photos suggested!
The one issue we had, and the reason I've given a four star review, is because there was a shop/bar/something nearby that seemed to play music all day and night. Obviously nothing to do with the accommodation itself, but it did stop us from sleeping on several occasions. We never worked out where it was coming from, but it seemed to playing all the time!
Overall, I would recommend this accommodation to anyone wanting to stay in Fira, but if you're a light sleeper bring some earplugs!