Pros
1. When teams are cohesive, the work can be exciting and rewarding. 3. Immediate leadership is supportive and encourages self-development. 4. Job security; if you are in a business critical role. There are many employees with 25 year tenures. 5. Interesting programs and opportunities for people who excel (the top 1%). 6. Information from management. The senior management always gives an accurate account the current situation. They never sugar-coat the situation; thereby making it easier to see pending job cuts or reorganizations are immanent.
Cons
Promotions are random and lateral moves are difficult. - New people are at an advantage. They are not tied into a particular function. Therefore, they can go up the food chain easier. To maintain business continuity, they will place new hires, instead of hiring within the firm, into lateral or new roles. It makes it hard for existing employees to learn new skills or improve their standing within the firm. Poor company sponsored development. - Only those who are on the edge get development/career advancement opportunities. It is a carrot of sorts to preserve your position. Otherwise, employees who work (normal people, not the 1% mentioned above) are considered too valuable to develop into new positions. They are given the slow track to improve their careers. This also explains the amount of employees who stay for 10 to 15 years in JPM. It takes them that long to get into management or senior development roles.