Also, "informal chat" style interviews (at least those without quantifiable scoring) can be fraught with bias. Did the CTO "like" the chat with the candidate because he was measurably technically qualified, or was it because he was a lot like the CTO in many ways, and their personalities gelled?
But on the other hand, I enjoy working more with people whose personalities and style also gel with me. So I don't really know if this is that big of a problem.
Communication is very important, and this is half the battle.
EDIT: But to answer your question: it was for an internship position, so an informal "talk shop" chat was more than enough to measure what we wanted.
Normally it takes a few rounds of technical interviews to get actual information from people who are less, let's say, "passionate". What would be better was if everyone could be as open as this person, so we would be able to just have the chat, instead of having technical questions and long interviews.
