I had the interview only a month ago and it is completely behavioural. As someone has already mentioned they look for weakness in your phyc profile and go from there.
My best advice is take a long hard look over your logbook remembering any flight's that stood out for any reason. There is nothing worse then starting to tell a story in the interview and half way through you remembering a better example.
Also be able to summarise your career from leaving high school till now. Keep it short don't talk yourself out of a job. Although they don't directly ask AIP questions if you are telling a story based on eg. Last light etc... They might dig deeper if they sense a hole in your knowledge.
Some of the obvious ones...
- 3 strengths and 3 weaknesses
- When have you had to help a work mate with personal problems?
- When have you broken the law? (Have an answer because they won't rest until you have admitted to something)
- When have you deviated from SOP’S?
- When have you made a decision that the group disagreed with?
- If in a senior position, how do you stay organised with tasks?
- Any incidents, accidents?
- When have you flown with a captain you disagreed with, disputes on the flight deck?
There is much much more and practicing any behaviour interview will help for this. Mine went for over an hour and I wouldn't wish it on any one, but no I didn't feel broken at the end of it. They just want to get to know you as best as they can in 1 hour so be yourself.
Good Luck!! 
P.S. Any body that has had their references checked lately, how long from then until you got the start date?