Interview was today, and took about 25 minutes (including a few fumbles of mine with the machine.) It pretty much went as described by others: most of the questions were right off the form, so I'm sure it was in part their equivalent of SPOT, but some were clearly followup and not redundant.

Update: didn't check the relevant email until I got home from work, but I got my approval email within about 15 minutes of leaving the center.