The process was incredibly drawn out. In total I had 7 interview stages consisting of email communication, initial telephone interview, 2 face to face interviews (one with two directors), a further 2 telephone interviews and a final panel interview.
Throughout the process I met with eight separate managers and directors. At every stage, I felt comfortable and encouraged to be myself. There is a heavy emphasis on finding out who you are as a person and a prospective employee, not just a number.
I found that not much planning was needed through the initial stages as the majority of the questions were trait based. However I was told that my thorough preparation for the panel interview was very much appreciated and set a great first impression.
The office is open, fresh and modern looking (as you would expect). There were a plethora of problems with technology for the final interview despite warning in advance that laptop and projector would be needed. The working envronment seemed quite and the office quite empty, but I take this as a good sign.
I felt more confident going into the last interview then when I came out! But this would obviously a test of character to see if I could cope under pressure. The feedback given was thorough and open and honestly given when asked for.
It's hard to advise how to prepare for any interview with Gartner, although I would say have a clear idea about what you want from the role and what drives and motivates you. If you have definitive ambitions, a desire to exceed your own expectations, and a strong reason as to why you want to be successful, then Gartner are the sort of company that will fit the role around you and help you achieve you dreams.