Pros
The best reason to serve in the U.S. Army is to gain leadership and life skills. You will also learn how to serve with and for others from all walks of life. During my service I have learned multiple languages, earned a fully funded Master's degree, traveled around the world, been responsible for multi-million dollar operations, planned and led (directly and indirectly) up to 38,000 service members. I have lived in the most amazing locations within the United States and the World.
Cons
Physical fitness is a tremendous positive to the U.S. Army. However, after 20+ years you will take your lean, fit, running machine of a body and run smack into the reality of AGING. What you were able to do for many years with ease will start to slowly become very difficult. Not only will the aging process slap right in the face but you will still be expected to perform alongside young 17 & 18 year olds as if you were the same. This is a harsh reality that bites you when you least expect it.
