For testimonials it would be best to go straight to Trip Advisor.
The first 203 reviews concern Hoi An Photo Walks, but since February 19 2019 the name has changed into Photo Voyager.
Why the new name? Check out this page!
Since doing tours in Hoi An I have received a certificates of excellence every year. If you keep coming and show your appreciation I am sure there will be another one in 2019!