Pros
Compensation is highly competitive and well-rounded. This includes a strong base salary plus many other monetary benefits (matching RSPs, stock options, annual bonus). Other benefits include health, dental, vision insurance coverage, group-rate for RSP purchase and a long list of preferred business partners (cheaper price for buying cars, train tickets, hotel/air fare, etc...). This is indeed the best place to learn train operations and transportation. If you are truly passionate about trains/transportation, CN is hard to beat.
Cons
Turnover (quitting) is getting higher among young employees and employees with less than 5 years of experience. The company is aware that it cannot retain people. Culture shock to some, where the mentality is set in stone by the management people, who have been here for 25+ years. Also be prepared to be brain washed and pushed to the extreme if not showing any passion for the train industry. You are 'expected' to become a train conductor/yard helper regardless of your profession (whether IT professional, accountant, HR recruiter or senior manager). The transportation industry is 24/7. Therefore virtually everyone is somewhat 24/7 on call. This can be very stressful to some.