My son was invited to participate on one of the USA Stars at-large teams last year. It was a terrific experience playing against some good teams from around the country, and he made some new friends at the same time. He also fell in love with NC. The NTIS event is well-run, the facilities are top notch. Highly recommended.
But go in with reasonable expectations. There were over 200 17U's there last year and USA Baseball only nominated 8 to move on to the next phase of the national team evaluation process. Enjoy the venue, play some good ball, and don't sweat anything else.
Good luck!