When I first interviewed with United Rentals one of their biggest pitches to me as the interviewee was that there was so much upward opportunity to advance your career internally. From what I've seen over 5 years there are frequent job openings within the company yes, but the management rarely hires from within. New hires are almost always brought on externally and good employees at lower level positions become locked in their position and become a victim of their own success. Rather than move up and trained in to a more advanced position, they are typically moved laterally with more responsibility and equal or slightly higher pay. This is often times justified on a lack of experience in said advanced position creating a catch-22; you're not able to move up in the company due to a lack of experience but unable to gain the needed experience in your current position. This pretty much leaves you with two options; gain your experience elsewhere, or settle in your current position.
The onboarding process for brand new employees is very sudden with very little training. You're pretty much tossed into the fire in a 'sink-or-swim' type scenario. Lucky, that is usually a much better learning environment for myself and I had great coworkers and mentors to lean on. This could be a pro or con.
There seems to be an imbalance in the amount that "say yes" gets pushed on employees in regards to taking sale/rental deals vs the amount of equipment that United Rentals actually has in stock to offer. This can easily create an 'overpromise and under deliver' dynamic with your customers which is very stressful if you're not careful.