Great experience for certain personality types; it's not for everyone.
Pros
Almost limitless opportunities available for honest, hard-working people. Good career coaching and mentoring available, good family support network. Reliable paycheck and good benefits for family, especially medical - while on active duty. Good networking opportunities for post-service career. Secure employment (if you don't do anything wrong you won't get fired or laid off).
Cons
Demanding schedule. Centralized promotions system does not eliminate appointment of few bad apples into positions of authority, in which service can be miserable, although overall good system. Pay is terrible and does not keep up with private sector counterparts. Very difficult to terminate contract in honorable manner (can't resign easily for better opportunity outside the Army).