Pros
Great place to mature and enhance your leadership ability. The opportunities for growth exponentially increase when you are deployed because there is more responsbility pushed down to the lower levels and less time to deal with beuracracy. There are incredible benefits associated with being in (medical care, schooling, support network for spouse) if you can deal with the frequent deployment rotations. Additionally, I have found it an incredible starting point for my civilian career. My experience is much richer than many of my peers, and I am granted more job offers at a higher pay grade.
Cons
As an Officer for the first few years, you have to be promoted at the same pace as your peers. You finally get the chance to distinguish yourself and get 'below the zone' promotions when you are a Major (about 7-8 years in). It can hit your morale at times. Additionally, the awards system can be challenging to maneuver if you are trying to recognize your Soldiers, and it can be frustrating. Finally, you have to understand that you are part of an incredibly large organization and your needs are not always aligned with the needs of the Army. (your choice of location, industry, synchronization of deployments, family vacation time)