My DD did a Professional Internship at Disney over a year ago, and she LOVED it!
When my DD was 12 years old, she saw someone holding a tarantula at a station at Animal Kingdom. My DD really likes insects and arachnids (not sure who her mom was!

), so she struck up a conversation with this person and this is when my DD found out about the College Program. Then and there, my DD decided she was going to do this.
Years later, we were visiting colleges. DD was talking to the heads of department at each university, and one of the things she asked was how involved they were with sending students to the Disney CP. The professor at Purdue mentioned, by name, the people in the department at Disney that he knew, and told DD she needed to go into the Professional Internship program, not the CP, because that would serve her better. Well, Purdue became her college, not in small part because of the connections between this professor and his Disney friends.
As a sophomore, DD applied for the PI. In her field, most of the PI's are college grads, heading into graduate school. Chances were slim my DD would be accepted, and the CP was her backup plan. Lo and behold, she was accepted, and she was the only one in her assignment that was not a college senior or beyond! She was thrilled!
The PI was a shock in many ways. It was a 6 month period away from home, far far away from home. If you are very attached to home, then expect the first month or so to be really tough, but you will come away from it with lots of personal growth!
Also, expect that the roommate situation may not be all the great. DD's roommate was from the deep South, we are Northerners. For us, we enjoy the differences in thinking and viewing the world, and DD especially could care less about political or religious differences.
Well, DD's roommate made life horrible for DD as time went on, always pointing out how heathen and unGodly she was being for being from the North, throwing out DD's things she felt were not to be in "her apartment", etc. The roommate was nothing like this when they first started corresponding, and was nothing like this the first two months, but bam, month 3, roommate was horrible!
The disadvantage of the PI is that the roommates and housing were done on your own, not thru Disney, so there is no one to go to for assistance. DD sucked it up, but thankfully the roommate was the only bad part of her PI.
DD did fall back in her college studies. She will still be graduating on time, as she is at school now making up classes over the summer semester, but for DD, this was a small price to pay. Not everyone would be so inclined to stay at school all summer, but the possibility is something to consider.
DD loved the internship so much, she is now a CP recruiter at her University! From the people she met and the connections she made while at the PI, and continuing on as a recruiter, we are hopeful that future employers look favorable upon her. As we have been told by others we know that do hiring for large corporations, as soon as that Disney experience is on the resume, they always give more consideration. We hope so!
My DD has no regrets, is considering doing the PI after graduation, and hey, visiting the participant is a great excuse for family and friends to go to Disney! I went 3 times in 6 months!
Good luck!