I'm going to be blunt because I do not believe in BS and don't like headaches.
DO NOT JOIN IF YOU ARE ONLY JOINING FOR COLLEGE BENEFITS. This is very, very serious business. Soldier are expected to maintain a very high-standard and complete the mission. Soldiers do die. Not just combat arms Soldier. You will be expected to serve as required by your contract.
ROTC is a college program. It is possible to get a scholarship, but not guaranteed. After you graduate college, you would be commissioned as an officer and would have to serve as a leader of Soldiers where the standards are even higher. You must be fully dedicated to your unit, the mission and the Army.
The GI Bill is a program to help Soldiers pay for educational expenses. It differs between the Reserves and Active, and now the Post-9/11 GI Bill.
When you join the military, you will have what is called a 8 year Military Service Obligation(MSO). This means that whatever timeframe you serve, the remainder of the 8 year MSO will be in IRR where you are not actively serving(on Active or as a drilling Reservist) but are able to be recalled. Near the end of your contract, if your unit or MOS is undermanned...you can be Stop-Lossed. This means your are retained in your current duty status past your initial service agreement(not to exceed the 8 year MSO). This is usually only done if your MOS is critical to your unit's mission and they are deploying soon. Usually those that are stop-lossed are discharged shortly after their deployment. Many have been recalled from the IRR to fill slots in deploying units, but it is not as common as it once was.
For example, you enlist for four years Active Duty. You will serve 4 years on Active Duty, with the remaining 4 years of your MSO being served in IRR status if you choose not to reenlist or are not eligible to reenlist. If your unit is scheduled to deploy and your 4 years ends during the deployment or just before, you may be stop-lossed until after the deployment. Conversly, you could be discharged then called back a year later to deploy with a unit that is short your MOS.
Seriously, think about all of this prior to joining. If you are not 100000000000000000% sure you want to be a Soldier. Don't join. This is a tough lifestyle. Yes, there are some nice benefits....but they are not worth it if you are not dedicated to everything that being a Soldier entails. Most of my headaches as a leader are those Soldiers who joined for college benefits and then did not expect that I would hold them to the Army standard....or expect them to be ready to deploy. One of those Soldiers flat out refused to deploy.....spent some time in jail and now is repaying their GI Bill to the Army.