Pretty much what webbster said up there. Here's my 2 cents:
1) Dont be nervous - these people are really here to help you and they want to see you succeed. Keep that in mind if you start falling apart.
2) Be professional - there were alot of highly qualified people there and I honestly could not rank anyone. Everybody seemed like they deserved to be there. There were even some Yale and Harvard students.
3) Be yourself - Mr. Taylor, Dr. Walker and Dr. Williams are such wise wise wise people and, just like Migs22 said from last year's thread, they'll be able to see any inconsistencies in your behavior with ease. This goes for the interviewers and current GEMS as well. The caliber of these people is just, wow.
As for me, it went great. My 2 interviewers were very laid back and it was very conversational, which was so cool. They made me feel very comfortable so I was able to open up easily. Again, remember that these folks want to see you win.
I hope everyone here gets accepted into the program. Hope to see u all in July! I'm gonna lay off the SDN fumes for a bit because this waiting period is gonna be brutal and mashing F5 nonstop for the next month wont help😀.