Vantaggi
Pfizer has good benefits (medical, 401K match, company car) and they tend to pay a competitive base salary with fairly decent bonus. I have worked in both the brand side and generic side of Pfizer and both have been good experiences. The company has changed a lot over the years but continues to move forward. For the most part, I've always had the autonomy to do my job and own my territory. Since there are so many different businesses, there are many opportunities for career development especially if you're willing to move and possibly work in New York headquarters.
Svantaggi
Since Pfizer is in constant change, there seems to be field force reductions nearly every year which can be unsettling. Also, the company has become more impersonal in my opinion due to the many acquisitions they have made over the years. There are many different businesses and many different cultures that have been put combined.