Pros
High expectations on performance are matched by levels of freedom. It is a principally (see below) meritocratic and relatively concensual culture: once you have invested up front in getting everyone on-board things can happen fast. In general you have a big say in your future development in the business and there are plenty of opportunities to move around the world with the business, if that is what you want.
Cons
The Mars leadership norm is extroverted and verbal, matching the businesses US origins. If you do not match this style, no amount of performance or personal development will get you into the upper echelons. The culture loves change and dynamism and consequently passively resists structure & systems, so lean processes are difficult to embed for example. The business is respectful of the individual but this must not be confused with caring !