I had a wonderful interview experience with the HP staff! There were 2 rounds of interviews (excluding the first phone call with the HR recruiter). I was told that I had a week to prepare and present for a case study during the 1st round of interview.
1st round of the interviews was with 2 hiring managers and they were very professional. 15-20 minutes were spent on introducing myself (the typical questions on working/studying experiences, why HP and personality/cultural fit). The next 20 minutes were spent on discussing the case study that I've prepared. The last 10 minutes was for Q&A. Both interviewers are friendly and polite.
I was scheduled for the 2nd round of interviews with the Director of the department right after the day I had my first interview. HR lady is friendly and swift in her responses.
The 2nd round of interviews was just for half an hour, which was more like a cultural fit and asking questions related to my future career goals. The interviewer is very professional as well.
In conclusion, my application process had far exceeded my expectation. In comparison with the past interviews I had with other companies, HP is by far the most professional and you could see and feel that they treat the interviewees with respect and kindness.