I applied online in early January expecting no response since Amgen does not recruit on my campus; however, I was excited to receive a call to schedule a phone interview in mid-February. The phone interview was approximately 40 minutes long and was very pleasant. It was a mix of technical and behavioral questions.
Later that week I received a call to schedule a flight down for their "super day" the following weekend. Amgen paid for and booked my transportation, which made my experience getting there much easier. I interviewed individually with four upper-level employees and had informal time with two newer associates. These interviews encompassed both technical and behavioral questions as well with an emphasis on potential fit with the company's values and goals; proficiency in answering behavioral questions and genuine interest in the company are key. If you don't have that, then the process may not be for you. Though long interview days are stressful and mentally challenging, I came out of it with a smile and an offer.