Not as big a thing as the papers seemed to indicate. The 'attack' on Cusco just before I left was during a conference on economic alternatives for Peru and there was one more alternative that the rebels wanted to remind them about. However, the organizers did consider rerouting part of our trip to put us a little farther away from a rebel stronghold.
There were only 3 people signed up for this trip and they ran it anyway. One of the 3 became ill at the last minute and didn't make it at all, so there were only 2 paying customers on the trip. We had 1 guide, 3 cooks (or camp staff), 3 wranglers to take care of 13 horses and mules and at one point where we couldn't take the animals, we had 8 porters.
I had no health problems the entire trip, just the usual cuts, scrapes and bumps that you expect when camping and hiking.
The trip was rated as difficult. This was because of its duration (23 days on the trail) and the elevation gains and loses that we went through. One day, we gained 6500 feet and then lost 3000 feet. The trip was easier because we were all fast hikers. You expect the guide to be strong. The other fellow along ran marathons. His fastest was one he ran 2 weeks before the trip which he ran in 2 hours, 34 minutes (very fast since the world record is about 2 hours, 8 minutes). Before that he used to do 'fell running' which is racing up and down mountains.
We saw some amazing ruins that few people ever see because of the difficulty of getting to them. I was very concerned about the state of these ruins, however. Some had almost been reclaimed by the jungle. For as important as some of these ruins are, their state was very disappointing.
Virtually none. One of the smoothest run trips I've been on.
One day we saw a farmer burn off the hillside that we had just walked down. They burn off the dry grass that the animals won't eat so that the grass sprouts new green shoots which they do eat. We also saw a horse fall off the trail over a 50 foot cliff and walk away.