Yeah, they are a pretty controversial group. Catholics to the "left" (conservative, post-Vatican 2 Mass attendees) and the "right" (traditionalists) of them have been critical of them, for various reasons. They've been accused of being a cult; of making their founder, Dr. Plinio, an idol; and of being too "gung-ho" about Fatima. Liberal Catholics, and leftists in general certainly don't like them. Overall, however, I have a positive opinion of them. A couple members of the TFP attend my parish in DC for the Traditional Latin Mass. They're nice guys.
It would be wonderful if other young men would take up this model for bringing the Catholic Truth back to Scotland. Most Scots really have no commitment to Protestantism at all.