I have been working at University of Pennsylvania full-time (More than a year)
It's a great environment with amazing teachers and faculty
The work can get very stressful
I applied online. I interviewed at University of Pennsylvania.
Process took about a month from application to offer. Consisted of a phone interview and in-person interview with all of the expected questions. Although I'm sure there are some great opportunities at Penn, I was put-off enough by my experience that I turned down their offer. Remember that you are interviewing them just as much as they are interviewing you. Don't be blinded by the prestige associated with the organization - have standards and enforce them.