Vanguard is said to be the Walmart of mutual funds, and most of the time, working there feels like working at Walmart. There are three main drawbacks: lousy compensation, few career advancement opportunities, and a culture that encourages slacking and turns a blind eye to incompetence.
The compensation probably compares favorably with other call centers, but it's dismal compared to other financial services firms. The non-cash benefits are decent (health care, 401k, etc.), but the cash compensation is really low for most employees. Most Vanguard employees work in the call center side of the business, where the work is very repetitive and low-skill, despite requiring FINRA licenses. I feel like many folks, myself included, were tricked into thinking that even a job in the call center was prestigious, but it's actually quite menial.
Because there are so many people with financial and economic degrees who get duped to work in the call center, competition for jobs higher up the ladder, such as in the Investment Management division, is fierce. If you work at one of the two satellite offices in Arizona or North Carolina, there is next to zero career advancement opportunities. If you're at one of the satellite offices, Vanguard will not pay to relocate you to a different office unless you are a very high-level manager; they would rather hire a new person from the outside than pay someone's relocation expenses.
If you are able to escape the shackles of the phone and make it into management or another support role, the pace of work slows down dramatically. Because Vanguard doesn't pay well, many of the people working there aren't the brightest or most ambitious people around. The corporate culture makes it optional for people to respond to their e-mails or answer their phones because slacking is not particularly frowned upon. A large percentage of the employees are incompetent. If you show any frustration that other people don't do their jobs, management gets mad at you for rocking the boat. If you're ever on a team or project or committee in any business unit other than IT, progress will be painstakingly slow because management doesn't want to risk leaving the laggards or dunces behind.
Take a job at Vanguard only if you have or can develop an exit strategy because you will regret working there more than a couple of years.