Pros
Harvard is a wonderful place to work. The work is challenging and I love coming in to the office every day. The vacation time is great (4 weeks PTO, 3 personal, and 12 sick days per year, plus a week off at Christmas), and include access to discounted wellness services (like yoga and massages), on-campus gyms, museums, and $40/semester classes at the Extension School. Where I work in Central Admin, there's a great work/life balance and I truly feel the organization hires very smart, ethical people who believe in the mission of Harvard. Mistreatment of colleagues is not tolerated by senior management or administrators. Good work is celebrated and rewarded.
Cons
Doing good work doesn't necessarily mean you'll be promoted. The promotion structure is based on the needs of the organization, not the individual's performance, so there's no guarantee that you'll be able to move up or make more if you do well, unless there's somewhere to move. This disincentivizes hard work, though most people that work here are overachievers :) Salaries are somewhat low, but for some, benefits make up for it if you take advantage of them. Space is tight and the offices aren't as nice as you'd think, given the amount of money Harvard has!