Bad History, Bad Guide. The Strange Liturgy of the Neocatechumenals
Are there cults in the Catholic Church?
The Neocatechumenal Way - A Fearful Danger to the Faith
Just search for "Opus Dei" on the FR religion threads, there are many mixed opinions. Opus Dei is named a cult in The Da Vinci Code, which I think only adds fuel to the fire of any erroneous cultish ideas about the group.
A quick read was enough to establish it as a Protestant movement. Sometimes heresy is so easy to spot it's not fun anymore. Kiko's catechism could have been written by Luther.