Is it competitive?
It's difficult to quantify. It has also changed since I was a participant, hence my original disclaimer.
The number of scholarships has dropped from 300 (mid-90s) to 250 (2017-18) due to reduced funding. I don't know when that change happened. The CBYX is also now administered regionally by 5 well-renowned international exchange organizations. 50 scholarships are awarded in each region.
Per the CBYX website, the regions are :
AFS: (Northeast) CT, DE, ME, MD, MA, NH, NJ, NY, OH, PA, RI, VT, DC
ASSE: (Northwest) AK, HI, ID, MT, ND, NV, OR, SD, WA, WY, and Northern CA
CIEE: (Southeast) AL, AR, FL, GA, KY, LA, MS, NC, SC, TN, VA, WV, and Puerto Rico
FLAG: (Southwest) AZ, CO, KS, NM, OK, TX, UT and Southern CA
YFU: (Midwest) IA, IL, IN, MI, MN, MO, NE, and WI
The East coast regions are supposedly more competitive because of a greater application pool. However, I can't verify with numbers.
There is a an explosion of postings on reddit, college confidential, Facebook groups, nytimes blogs and student blogs all attempting to describe the application process. Someone even wrote an ebook about it. Wow... it was overwhelming combing through these links trying to find a answer of true acceptance rates, but in the end the only numbers I found are based on rumor, not fact. So I have no numbers.
The application is very similar to applying for college. Sections on the application include basic personal information, teacher recommendations, and several essays. Semifinalist interviews include both individual and group interviews.
My best advice: can they give an honest, meaningful answer to the question "Why do you want to go to Germany?".