The donkey steps lead down to the old port at the foot of the cliffs in Fira. It's a fairly easy if somewhat monotonous walk down, with nothing much to see except donkey doo until you get so far down that you start to get decent views of the port ahead and Fira behind. It's a much harder walk back up, especially in the full sun as there's no shade at all.
The donkeys all congregate at the top and the bottom, so once you see a large crowd of tethered donkeys you know you're almost at the end. It would in some ways be useful if they tethered some donkeys half way up, because it is about half way on the walk back up that taking a donkey starts to become an attractive option. Well, it does until you meet one careering towards you, occupant on back and owner nowhere to be seen. The donkeys know their way and don't need to be guided, though their progress is somewhat erratic and those on foot do well to stand well back - whilst also trying to avoid being crushed against the wall.
How many steps are there? I believe it's something like 590. At the top the numbers are painted on them, though this is right at the VERY top, in the town (picture 4), where knowing how many steps you've climbed has become irrelevant. Again, it would be useful to have numbers painted every now and then, so you can at least gauge how far is left. The best gauge for me is when you reach the blue painted wall at the top (picture 3). At this point there's only one more bend to negotiate and the end is nigh.