Gap Years have numerous benefits: generally the most common one cited is increased maturity. While much of the data currently cited is based on the UK model, pioneers in research are now tracking in greater depth the objective benefits for US students taking a Gap Year.
That being said, there are reams of anecdotal/qualitative data about the myriad benefits of Gap Years. Generally, these include: increased maturity, greater "ownership" of the student's education, increased self-awareness, greater global awareness, fluency in a foreign language, and of course the self-confidence earned from successfully completing a putative Rites of Passage through their Gap Year is consistently listed as one of the enduring benefits
On an educational level, universities are reporting an increase in GPA, greater engagement in campus life, increased likelihood that students will graduate 'on time' or within four years, and of course greater clarity with career ambitions. Furthermore, students who take a Gap Year are 90% likely to return to university within one year: in essence, Gap Year graduates are MORE likely to attend university than their peers. Finally, while we don't suggest this as a primary motivation, many students do report that taking a Gap Year enabled them to both get into better universities, and that with the summary of their new experiences they were better able to identify universities that fit their personalities and career ambitions.
On a personal level, students who have completed their Gap Years have reported being as much as 75% more likely to be "happy" or "extremely satisfied" with their careers post-university. On further examination the defining characteristic to their statements seems to be the sense of defining their own version of "success" that typically rates highly service and the commonality of mankind. 60% of Gap year graduates said the experience either "set me on my current career path/academic major" or "confirmed my choice of career/academic major", and 88% said that it added to their employability.
As for the social benefits, one of the most common things heard from Gap Year students is that they actually have something interesting to say… in other words, with such a packed year of life-experiences, there's simply much more to share, relate to, and communicate. These personal anecdotes can come out in conversation, in essays, in job applications, podcasts, etc.