It's easy to get caught up in the $1,000/night hotels in Oia so I wasn't sure what to expect when I booked the Altana. It turned out to be an amazing experience and one of the highlights of our entire vacation.
One thing you don't find in a lot of guides or reviews is that Imerovigli is the highest point of all the cliff-side towns. The Altana had some of the best views overlooking the main town of Fira and the rest of the island. While Oia is a nice place to stay, it's somewhat secluded by narrow winding roads to get to the northern tip of the island. Imerovigli has a couple good restaurants nearby and you could walk 20 minutes through town to get to everything in Fira (I would not recommend staying in Fira due to some of the clubs and crowds).
What really set the Altana apart though was the service. Cristos and Marius (sorry if I misspelled your names) were superb hosts and will make top notch cocktails customized to your tastes. They knew all the best places to go on the island and really helped us navigate all the tourist traps. Literally not one of their recommendations was bad, which left me wanting to do as many as possible in the four days we were there.
Overall a great experience and I look forward to going back one day.