1- The most important issue to care about is "Weather Forecasting". cause of the wide catchment and narrow valley it has a high potential of being flooded (as it's every year). If it happens while you are there, then there is almost no chance for life. All 11 members of a group from Qazvin (Iran) were died cause of the same reason at summer 2005.
2- Please check the belay supports and don't trust them at all (Annual floods may caused damage to them)
3- Just for your safety please don't jump from the top of waterfalls. because you don't know how deep they are. If not deep enough then you'll be in trouble!
4- Each time you may see a new face from this canyon. It depends on annual floods.