Vantaggi
I worked at a Plant, so my experience is unique due to the Plant-level being somewhat isolated from Corporate policies and practices. In general, I enjoyed the people and the freedom from sometimes domineering Corporate upper-management. MBM, although sparsely practiced at the Plant-level at GP (will talk about in the Cons section), is a fairly effective way of dealing with HOURLY employees and making them feel more valued.
Svantaggi
Because GP has so many Plants operating under so many different kinds of people and departments, even in 2016, communication was horrendous. I had the displeasure of working under a manager who lacked any basic communication skills and relatability, but because they performed well, was lauded and considered a major asset. I was never asked to give feedback on their performance. I was never trained. Over year long period, my manager probably spent two hours explaining processes and the business to me. Instead, I was forced to write up more things I could be doing better and given criticism after criticism. There was also a major disconnect between all employees at the plant regarding MBM. You can hold meeting after meeting about continuing to push forward an MBM culture, but the more you push people (most of whom just want to work and go home), the more they mock the system behind your back and see it as almost a cult. Most things MBM preaches are common sense anyway and if your a decent person with a brain you do them without thinking.