We decided to do the Salkantay trek instead of the Inca Trail because it was supposedly much more of a challenge. And that turned out to be true.
The altitude gets to you much more than you would think. Most people in our group had trouble adjusting to the altitude and had headaches and such. Apart from that the nature and sights were really diverse and beautiful and all that paired with a charismatic guide made for a great and unforgettable experience.
I would recommend the trek to anyone who is fairly fit and would also recommend to arrive a few days earlier to adjust to the altitude.