Shortly after applying online, I received an invitation to take their Hackerrank test. This test had a time limit of 72 hours, so I made sure to have a relatively open weekend so I could do as much of it as possible. Due to confidentiality, I cannot reveal the exact question, but it was a good exercise in data structures, matching and optimization.
The requirements for the test, however, were pretty much terrible. In addition to the grammatical errors (of which there were plenty), there were a few contradictory requirements. In addition, the test case output remained hidden, so it was a chore to infer which of requirements was correct. Despite this, I managed to get 24 of 27 test cases to pass, and I figured that I would be disqualified at that point.
Surprisingly, I received an email requesting a pair programming/phone interview with one of their engineers. This went quite well, and I was asked to implement a lock-free queue after some discussion of my experiences. I did this well enough that within a half hour, I had a request for an HR phone screen.
This one also went well, but it was more focused on them selling me on the company. I only had to answer a couple of questions like "Are you open to relocating?"
Following this, I had an on-site interview, which was also a good experience. The engineers with whom I interviewed asked some tough questions (make sure you're fully up to speed on data structures and optimization techniques), but I answered all of them, including how my answer for finding local minima in a 2-D array was more efficient than that proposed by the interviewer.
Leaving the building, I thought I had done extremely well, but I received an email later in the week informing me that they were pursuing other candidates. It would have been nice to receive more specific feedback, but overall it was a good experience.