I ran across a couple of their tour groups while I was in Africa. The only thing I didn't like about them was that they took people into the parks like the Siringeti in big double deck buses instead of the smaller quieter jeeps the other tour companies used. The Gap tours mega buses would plow into an area in a cloud of noise and flying dirt and totally disrupt the wildlife that everyone else was trying to watch respectfully at a distance.
One time there were two lions stalking up to a watering hole where there were a bunch of zebras and wildebeests drinking. They were slowly moving in to set up their dash to try for a kill when in zooms the Gap bus. The lions went running off one direction and the potential prey another. Those of us who had been patiently and quietly sitting there hoping to see something interesting were left shaking our heads on a cloud of dust.
My guide said the Gap bunch were always doing that and that all the other guides found them really annoying.