We stayed in Santorini in 2008 and again in 2012. Unfortunately it's lost it's appeal. It's still one of the most beautiful places in the world, however a few fundamental things are ruining it.
It's become too commercialized and over populated. The traffic round central Fira is appalling and even parking is the issue.
The main thing that disappointed was that some traders have become rude and arrogant and treating tourists as second class citizens. I think they are forgetting that Santorini's success and sustainability is wholly reliant on tourists. We come here to have a nice time and spend money. We do not come here to be ripped off and treated badly.
We will not be coming back to the island and feel sorry for the hard working people who's livelihood depends on us tourists.