It is an alternative to traditional grade-level, drop off CCD programs, and is designed to involve the whole family, and the rest of the parish in an inter-generational model. Preparation for sacraments happens at other meetings outside of GOF gatherings. GOF is usually once a month gathering, 2-3 hours, with program, some teaching, crafts, stories, games to reinforce lesson.
If you follow the curriculum, and if every family member attends every session for 6 years you would get a fair intro to Catholic doctrine, as each year’s programs are built around a certain theme. year 1 sacraments, year 2 Liturgical year, year 3 saints, year 4 commandments & beatitudes etc.
Trouble is the underlying assumption that all Catholics needing catechesis belong to intact families who are highly motivated to attend this program over several years. In several recent books on family-based or intergenerational models which critique the programs, authors state that they found kids were still NOT learning the basics of Catholic identity - the prayers, devotions, the Mass, sacramentals, social justice etc.
in a parish that has a hard time attracting and training catechists this might be a good alternative, but bear in mind, there will be a lot of kids who fall through the cracks and will not be reached.