Campus interview is easy, just talk previous working experience.
Phone interview is not hard, just anwer the question about "the most difficulty of your work..."
The day before onsite interview, there is a dinner to meet engineers in MS.
Onsite interivew is intensive. Talk to 4 person, and 45 minitues per person. Everyone will give you a like behavior question, such as "what would you do if something happened..."
They are very nice persons, every student is exciting about the interview, but not everyone can get offer.
By the end of interview day, the offer will be known.