Submitted an online application at the beginning of the year. Was contacted by a university recruiter about a week later. I informed the recruiter that I had an offer with another company that needed a response within a week and the recruiter was able to expedite the process. That same day, I had a phone interview with the recruiter and was later informed that Microsoft would like to fly me out to Seattle for a final round of interviews.
Flew out to Seattle later that week. Microsoft paid for everything including the flight, hotel, and all transportation. The next day I had the interviews. First I met with a recruiter who would be my main contact. The recruiter informed me about what the plan for the day was and tried to get a better idea of what my interests were. Afterwards, I was shuttled to my first of four interviews. These interviews were more technically focused. Often the interviewer would tell me about the company and then ask a few problem solving questions for me to solve. I was able to ask questions to them near the end. The interviews took about 45 minutes each, and they were all with people in the same department I would be interning in. One was over lunch.
Overall, the actual interviews weren't very stressful. The interviewers were easy to talk to and seemed very honest. It was easy to tell that they really liked working at Microsoft and tried their best to sell it. My day concluded with a return trip to the building where I met the recruiter and a wrap-up interview with my recruiter. Microsoft did give the option of staying an extra day to do some sight-seeing, but due to scheduling issues I was not able to do any.