How honest should one be in a PhD exit interview? I will be graduating with a PhD and so I have one coming up soon. It seems like a new trend in academia. It is usually for all graduate students who enter the program when they leave it, with or without finishing. For example: ece.rice.edu/~suman/grad_council/exit.html. It is not to be confused with the thesis defense and will have no impact on my graduation. The interview is going to be with only the graduate program coordinator in my case. I assume, though, he will share the input with others including my advisor.

I searched the web and found answers for exit interviews in the corporate workplace instead. Most of the websites seem to suggest not to be completely honest to avoid burning bridges. These websites also suggest that HR people don't make any structural changes anyways to accommodate your concern. Can I extrapolate these ideas to a PhD exit interview? Is there anything to be gained by being honest in this interview? In particular, should I be honest about the advice and guidance I received from my advisor especially if I feel I didn't receive enough attention and advice from them? I know this is a common complaint among graduate students, should I be honest nonetheless?
I had an exit interview when I left my graduate program and I have also had exit interviews in industry.  My feeling is that exit interviews in Academia have the potential to be productive, whereas in industry, it's mostly just HR covering the company from liability.

There is probably no perfect answer, but I would say that you should be honest while remaining professional and constructive.  If you have criticisms of your degree program, try to keep them general (don't focus on your PI or your lab unless they ask about it).  My program director was very defensive when anyone criticized the program, so I was careful and tried to provide solutions to my criticisms.  I do think that he took some of the suggestions to heart, such as moving the qualifying exam so that it did not overlap with certification board exams.

In my opinion, the exit exam is not the time to bring up anything along the lines of harassment, mostly because I don't think it would be recorded properly, as random_non_bot_person mentioned.

Industry is different.  Exit exams seem to be only there to cover the company.  If you were sexually harassed at the company, HR wants to know so that they can prepare for a legal defense (I'm guessing, I'm no lawyer).  They want to know if you were fired, they want you to understand the implications of any NDAs that you signed, and they want to know that you aren't going to sue them.

Summary: Academia exit interviews have some potential to change the program, but is highly dependent on the program itself.  Industry exit exams will almost definitely not change a thing.