Vantaggi
Great location. Get to work with some of the most talented people in the industry. Great exposure given the firm runs so lean, although this is a double edged sword. If you're a star and your boss/upper management likes you, not too difficult to move up with time. Tuition reimbursement and solid 401k. You can leverage the name for a better, more well paying job elsewhere which is what most people do. This is probably the best part of PIMCO.
Svantaggi
The compensation is laughable. If you look at competing firms for the same role, they pay significantly more, in some cases double. Even if you get promoted to VP, which they make more difficult than it has to be to obtain, it's a small bump in overall pay and not up to par vs the rest of the industry. So you end up having a bunch of talented people who are overworked, understaffed, and underpaid which leads to very high turnover. Executives at the firm don't get this so they deal with the turnover, which is probably more expensive than just paying their employees well. Pretty horrendous strategy IMO. Every year there is a new excuse as to why comp is flat or below. Also a very top heavy organization where PM's are treated like gods. Technology is also behind rest of the industry although they are making a sizeable investment to turn that around.