I was looking through the feedback from my 2005 PDC talk, and I noticed an interesting contradiction. The written feedback indicated that the first half of my talk (wherein I talked about memory management and "paying your taxes") was more favorably-received than the second half (on user interface issues). On the other hand, nearly all of the questions people asked afterwards were about the user interface issues. "Wow, that thing about parent and owner windows, I think that's why my program is crashing," or "Gosh, synchronized input explains this problem we've been having."
I've been told that "the quality of the questions you get after a talk is the best indicator of a talk's success", so I'm inclined to go with the people who were more interested in the second half than the first half. (Of course, the increased interest in the second half might just mean that I did a worse job in that part and people needed to come up to me to clarify the things I did poorly!)
Maybe my next title should be "Story Time with Raymond". It could be the only 100-level talk at the PDC.