HELP as an organization places college-aged volunteers in countries around the world to work on "substantive development projects". After you choose the country you want to volunteer in, you are placed with other teammates and two country directors, who you will live with for 6 weeks-4 months.
I found the experience at HELP to be completely dependent on personal drive, dedication, and attitude. HELP does not hand anything to you--you must develop your own projects, find partner NGOs to assist, and develop each project and partnerships (for the most part) on you own. This worked perfectly for me, as I already had a plan of who I wanted to partner with and an idea of what I wanted to accomplish. Others in my team found this model very hard to deal with, mainly because they wanted other people to tell them what to do and not be expected to figure it out for themselves.
Don't expect this experience to be filled with "substantive" development work either. The model of putting people there for 4 months tops does not allow for much. The majority of people will be there for 6 weeks-2 months, which is even less time to make a difference.
Overall, I had an amazing experience, though many did not. It is what you make it. If you want to work with people more serious about lasting development, HELP is not the place for you. I learned so much, but I believe most volunteers were there for the international experience, and were not interested in development.