Our local guide Neil was fun to be with. Gave us a good feeling for Harlem and its history, in a fun manner typical of the local culture. The gospel mass was interesting and pleasant, and with the group you get priority and skip the line. There is an element of awareness of the presence of tourists, who are indeed explicitly welcomed, but you get a very good idea of the major role of the church in the community and the mass is authentic.
Note: The tour description refers to a light breakfast, which didn’t materialize. Not a problem for us as we had our breakfast before the tour, but worth bearing in mind for planning purposes.