Pros
There are places within the Army where you will never feel more rewarded for a job well done, although they are hard to find. It generally doesn't get you so much as a pat on the back, but you'll know when you've been a part of history in a good way. If that is enough for you then you will be pleasantly surprised when, as a reward, they give you some colorful ribbon to put on a uniform you seldom where. There are many opportunities that make a career in the military very worth while, that you will not likely get elsewhere. Camaraderie amongst your peers is not guaranteed, much less with your supervisors, but when it exist there is a sense of the entire group working as one (Hence the old slogan). Advancement is a fairly unique system and varies depending on your level of seniority. You are likely to be advanced with your peers as it has become very systematic. Travel to places where most will never see is almost guaranteed, schooling not available to 99% of the population is guaranteed, the opportunity to be part of history is practically guaranteed and there will be rewards long after you have left the military.
Cons
There are numerous cons, and most have heard all about them. The simple fact is that people get promoted partially due to tenure which results in people incapable of leadership being leaders. There are so many variants available in each career field (and there are hundreds of career fields) that seldom does a senior leader understand the roles of most of his/her subordinates, which in turn leads to some being neglected as far as funding for training and equipment to the favor of the ones with which he/she is familiar. There is a great amount of wasted time, which becomes an accepted fact of life. The military (government as a whole in fact) is an expense not a profit making entity, however that is little excuse for inefficiency. Personal/Family lives of soldiers are negatively effected as a result of being deployed, so when not deployed if the wasted time could be avoided this would help the moral and personal/family lives of the soldiers. There is no organization that you could be employed by that could have more control, normally to your detriment, of your personal life. Many of the rights afforded citizens, due in large part to the soldiers, are not afforded to soldiers. The Uniform Code of Military Justice empowers the same leaders mentioned above (the ones promoted solely due to tenure) to seek legal punishment for laws no other citizen is subject to (such as failure to obey a lawful order, read 'do what your boss tells you to', for which the maximum punishment is 1 year confinement). I have seen it used for good reason and I have seen it used without reason. When it is done without reason, there is no retribution to be sought by the junior member.