As per my sponsor, who is a very good friend of mine, the interview experience was just very informal in a way that he (sponsor) shared everything about our acquantances in the past 23 years...he informed the lady interviewer every detail of our activities whether related to our family and our former work. In other words, he did not waited any longer for the interviewer to ask him more questions instead he shared the stories of those moments that we've been together and the details about my family as well, and that's it, the interviewer was very satisfied and convinced of our "connection".
At the end, the interviewer just asked how my sponsor could be able to help me settled in Manitoba, without any words of doubt, he expressed his willingness to support me all the way from accomodation to finances upto the moment we really settled well.
The bottomline here is that, once the sponsor is relaxed and able to composed himself during the interview, definitely not feeling nervous, chances are, the interviewer will be convinced that both (sponsor and applicant) are really friends and good favor will come very soon. That's for the case of GS applicant.
Glory to God!