Pros
Name recognition. Great access to talks, events, etc. Good benefits. Most labs are probably well funded (but that wasn't the case for the majority of my time here).
Cons
I would imagine the experience is quite heterogeneous, i.e., depending on who you work for it could be amazing or downright horrible. Each lab really functions as an independent small business. I worked for more than one lab over several years, and had mixed experiences. One issue is that there is an obvious lack of departmental oversight for individual labs, from a management perspective. Really not enough "manager" types -- most of the people that end up in management roles get there because they are good at science (read: securing funding and publishing). While the system isn't set up for this in some sense (not enough funding to justify hiring MBAs), there is really no excuse because it undermines the mission of the university, and actually leads to a lower quality of science being done. There were times when I honestly feared for my safety because of the way my boss acted, and higher ups were not unfamiliar with this person's pattern of behavior but chose to ignore it due to sunk cost of having already invested time/money into them, and knowing that the tenure/reappointment system would probably cull this person out eventually. There is also a 'game of thrones' like vibe to the promotion system (at the medical school at least), the stress and ethical uncertainty of which trickle down to the level of research assistants, unless the PI actively works to shield them from it For those seeking graduate degrees and using this as a stepping stone, know that there is a lot riding on one person in a small lab. If you find you don't get along with the PI, you can be pretty sure that you'll get a lackluster, obligatory recommendation letter from them, which will definitely hurt your chances of getting into graduate school. This process is still completely subjective and not systematized in any way - and yet it is, probably for most people in these roles, the single biggest form of compensation from the work. That is a lot of power for one person to have over an employee. I have seen it abused. Another thing - I don't think I got one formal review in almost five years of work. But it doesn't work that way for professors - they are scrutinized. Why shouldn't the department take an active role in encouraging professors to learn management and to scrutinize their employees by setting reasonable goals and requiring reporting on them.