Pros
Power gives you all the tools to be great at your job whether its training courses, support from the office (BIM, 4D scheduling, a well rounded and large QA/QC department) or simply reaching out to others within the company. Starting with PE's, Power's curriculum allows for everyone to be working on a level playing field and the expectations of you as an employee are perfectly clear. Power has a simple philosophy, do the right thing and build relationships at all levels. I've never felt I was in a bad position and my managers/executives have always supported my decisions when sticking to these principles. This is why Power is so successful. Project to project Power is consistent in performance and ethics. What you see is what you get.
Cons
They don't pay top dollar. You are rewarded with job security even in the worst of times and you get the opportunity to work on jobs that few other companies can perform.