Very pleasant and efficient interview in general. We had an initial screening stage with very generic technical questions and a second stage with a take home assignment with pretty generic science concerns. One problem is intentionally leaving everithing too underdefined and generic, even though the interviwer always had one specific answer he wanted to hear. Thus, any answer could be correct (but from the interviwer perspective, they're all incorrect, given that he wants to hear his version). Another problem I found is the lack of criteria for evaluating the assignment (same reason as stated above), and the lack of feedback. Given that the interviewee spent a bunch of hours, a single feedback on what went wrong is not much to ask.