This program is a godsend. I fly between Canada and the USA, combined with Global Entry, it saves me so much time - I even noted it as a tip on the YYZ airport.
The main thing is that scheduling your interview implies a very long wai, usually a few months, so I would suggest applying to get one now. The interview itself is short and they want you to confirm your intentions and information, then they take fingerprints and an iris scan. However, I came on time and only waited a few minutes, leaving happily after 20.
A 4.5/5 experience. A 5/5 product.