Pros
Great focus on core business of lodging and a desire to remain ahead of the curve or at the very least, stay competitive when it comes to adopting new business strategies and trends. Marriott does a great job of recognizing and promoting talent from within - I literally went from entry-level to Department head in less than 3 years. The hospitality business in general is not for everyone but if you are inclined to love it, you will like Marriott more than the other choices in my opinion - better than the franchise management companies that I've had experience with for sure. Please note that all of my experience comes from working at full-service Properties, I can't really speak at all to the experience of Limited Service associates and managers.
Cons
The Hospitality business is subject to the whims of the economy so that is tough - not only do bonuses and such rapidly shrink away but contingency plans wait like wolves at the door when travel (and, of course) revenue drop off as companies tighten the belts. Also, to advance to bigger and better things it is often necessary to move to larger markets and often this means places like Orlando or resort areas that are nicer to visit than they are to live in. Since Marriott is a largely de-centralized company when working at Property level you feel a bit isolated if you are not afforded the opportunity to attend training and conferences.