Do you have any advice for potential travellers?
You need to treat all water so plan appropriately with filters or tablets. In several places you need to add double tablets so they can run out fast. We were treating around 3L of water per day while trekking. It may be useful to have 3x1L bottles not just 2 as refills were not available on all days.
You may get away without river crossing shoes. We did as the water was low and we crossed in bare feet. After some rain you may not be so lucky.
When it rains it pours and got cold, don't expect hot weather all the time. The nights can be very cold. Most of our group had light weight down jackets or thick fleeces. We had frosts on the higher campsites overnight.
As with all trips of this type there is a chance of getting ill. Some of our group had mild stomach upsets and a well stocked first aid kit makes things more manageable.
Come prepared with patience if you get the visa on arrival. It took us 3 hours to get the stamp. It is frustrating but then most of our group were in the same queue. Expect equally tedious processes every time you go through the airport.
Do some research on what to do in Addis on your return. It is not the most interesting of cities for tourists and a bit of research may mean you get more out of the free day.