Porter is notorious for flight delays and cancellations.
I fly between Toronto and New York every other month and have yet to fly when there has not been a delay. The severity of delays have ranged from 30 mins (which is not bad) to several hours (horrible if you're like me and your time is valuable).
The perks of the lounge are great but I've wasted too many hours of my life sitting there waiting for delayed flights.
Porter is a great choice for leisure travel but NOT recommended for business travel or any other time when you just can't risk being late.