Starts with a 30 minute phone screen, followed by at least 1-2 hours of additional phone interviews. Then a take home assignment which they say "no more than 3 hours" which seems semi-reasonable, but if you actually take your time on it, I would say expect to spend the greater part of a day on it (4-6 hours at least). Don't expect any feedback on your work. This is then followed by an on-site that is at least five hours with multiple interviews - some one on one, some with a panel. Don't expect any expenses covered besides travel and boarding. The worst part however, is that even after doing the long homework assignment, you're expected to sit through three separate one-hour coding interviews where you answer typical LeetCode/HackerRank questions on a screen-share. Expect LeetCode easy/medium algorithm brain-teaser type questions, and if you aren't up to snuff with these (like I wasn't), don't expect an offer, despite any other relevant job experience. Most questions come directly from Cracking the Coding Interview and can be found on LeetCode. It seems these guys are trying to mimic the typical FAANG interview process, for better or for worse.
If there was any indication of how much time these guys were going to require during the interview process, I would have passed immediately. Judging by other reviews here, this seems like pretty common criticism. Expect total disregard for your time. For the most part, I enjoyed the face-to-face conversations and found them relevant and not superfluous, as some interviews are. However, there is a subtle degree of elitism during the entire process that taints the environment.