I've never been canyoning before, and I have to say this was a great starting experience. It was well led by Angel, who was completely professional and safety conscious, but never missed a chance to have some fun (I won't say how so you don't miss any surprises). He was very conscientious and was able to meet individual needs while keeping the activity running smoothly. He had a great crew with him as well. Vasili was very personable and engaging, and between the 2 of them, I learned much about canyoning and abseiling (they are very good about teaching technique) as well as the mountain gorge through which we passed.
The area was beautiful and the water cold and refreshing. I did the Nefeli B trip, which was longer, and which I would recommend if you have the time and are unencumbered by other concerns. It is not harder than Nefeli A, and adds more to the experience with more drops/falls, as it is a continuation of Nefeli A. I believe there are 8 all totaled between A and B, but don't hold me to it. I experienced small rappels, jumps into pools, slides into pools and larger rappels. I had some worries that the rappelling might have been scary, but not really. You just focus on the technique they teach and all is good. It is not too physically taxing, and the cool water keeps you just that way. In some ways the most strenuous part of the trip is the hike back to the village.
If you are in Zagori- Go. Do it. You'll love it