Vantaggi
Vanguard spends a lot of time and money training new employees and bringing them up-to-speed. Their main philosophy, from an employment perspective, is to hire the best and brightest right after graduation, and then try to bring them up the ranks. Vanguard also tries to fill all of its positions internally, and can be difficult for people from the outside to get into, at least for the higher level positions. Many of the people there have been there for 10+ years. Also, their retirement plan and other benefits are great, even if the pay is somewhat low compared to the average.
Svantaggi
As a financial services company, it tends to be reactive, from a technological view at least. Also, the culture is fairly conservative, such as the "actual" dress code is actually one better than the "official" dress code (i.e., if the dress is business professional, which is supposed to be a shirt an tie, most people wear a full suit). Also, many of the people started there right after school and have been there for 10+ years, which fosters somewhat of a holier-than-thou attitude, in terms of companies to work for.