The views are absolutely fantastic on the way from Fira to Imerovigli. And you pass by many nice hotels or cave houses. Highly recommended activity!  Please be aware that the walk from Fira to Imerovigli is almost exclusively uphill, and during the summer afternoon, it will get very hot.  If you will be visiting Santorini during the summer, this is a walk best enjoyed either first thing in the morning or as the sun is going down.