Phone screening with a recruiter, then if they think you are a good fit, they invite you to their office for three 30 minute interview back to back with 3 different people, following with an assessment test that is designed to see your mathematical background. After the interviews, if they decide to move on forward with you, they do a background check before hiring.
The first time I talked to the recruiter on the phone was uncomfortable/awkward. Then, when I was invited to their office, I arrived early and checked in with the receptionist, but I had to wait for 30 minutes for the recruiter to come get me, which resulted in rearranging the interview schedule for the day. However, the interviewers I talked to were very friendly, open, and willing to share their experience. I liked all the interviewers I have talked to.
Overall, my experience with the interviewers was great. They could work on training the recruiters to be more on top of their things and get back to the interviewees with a reasonable time frame, for I had to reach out to the recruiter multiple times (phone calls and emails) to follow up since she was not very proactive about it.