Merck was once "The Best" but those times are long gone and never to return.
Pros
Benefits are still above average when compared to other Pharma companies. There still are a few high level executives who care about their employees, but they are rare.
Cons
Unless you are one of the "chosen" or "elite" there is no advancement. There are plenty of empty rationales behind why one is beyond qualified but will never receive a promotion. If you are a college educated, non-exempt then you can certainly forget ever moving up within Merck. Also, salaries, at the lower level, are never reevaluated. Cost of Living increases, as well as insurance premiums on the rise every year, aren't taken into account at our yearly raises. These 1 or 2% raises, for being top performer, do not cover the 4-6% increase on out of pocket expenses for benefits alone. Lower levels are also never given stock options.