The interview process with KungFu was completely ideal. They were highly communicative the entire time, and I knew exactly what to expect at each step. Not only that, but they worked extremely quickly -- I think in total it took barely a week, and that includes a handful of initial phone screens, a fairly extensive on-site interview, and then an offer. A very impressive turnaround time, especially when compared to some of the other opportunities I was pursuing at the time (one of them took 5 weeks just to accept my initial application; another took 4 weeks and I was still only halfway through their interview process).
Had some initial phone screens where we mostly discussed previous experience and projects. They do a lot of work with NLP and computer vision so a lot of the more pointed technical questions asked about familiarity therein. The on-site interview was similar - a few general ML/stats/probability questions, a few more specific questions about NLP, many other questions about my previous experience and how it could apply to the problems they work on.
All in all it seemed like an excellent opportunity. They clearly have an extremely intelligent and friendly team there, making for an environment highly conducive to mutually beneficial learning. The only reason I didn't accept their offer was because I got an offer elsewhere that was too good to pass up, but I wouldn't hesitate to recommend KungFu to anyone.