Gee. I'd hate to get a flat at the bottom of that hill and have to walk up. Nice shot.
Its about 1000 feet or so. If you wish, you can rent a mule to carry you up. There is also a funicular up, its barely visible to the left of the path.
Sharing the path with the mule's is not necessarily as bad as it sounds, as the path is cleared reasonably well.
When I visited Santorini, I chose the funicular up, but walked down, much easier than way.
It is really a nice shot.
Alan