Who you work with, and what you work on, makes a lot of difference.
Pros
Learn a lot and rise faster ( compared to some places). As long as you are competent you will be able to stay for a long time. Because the firm always needs more people they will be flexible and work with you if you ask for flexibility or other changes. A lot of the partners and higher-ups are great coaches. Exit opportunities in related fields are always available. Recession proof job.
Cons
Some people and situations make the job harder than it needs to be. People above you are there just because they never left, people below you are there just because they showed up. Some of them happen to be great but some of them are incompetent, plain mean and/or textbook examples of personality disorders. Good people constantly leave due to this, and that adds to the unpredictability of the job. Bad apples ruin it for everyone