Excellent, full of great conversations, and smart people. They will expect you to think critically and respond to constraints on the fly. The best thing that you can do to prep is practice solving different kinds of problems with a repeatable, reliable approach (i.e. map out constraints, broad overview of solution to satisfy all constraints, visit constraint or requirements individually and try to optimize your solution.)

I had behavioral interviews and then 4 in person interviews. The behavioral was straightforward. There was also a data query interview where they taught you a new "language" and had you execute basic queries in it. Then there was a system design interview. I had two of these. The last one they asked me if I was deployed to the moon to identify new species of alien what kind of system would I build.