napro is loved by many, I unfortunately found it not so good. I felt that they claimed to treat everyone as an individual, but then everyone was treated in almost the identical way.
It is a glorified version of tracking your cycle by monitoring your cm. Personally, if I had my time again, I would use the money I spent on Napro buying a babycomp/ladycomp monitor. But as I say, I am biased as I had a bad experience with them.