Hi chrispatrickGA!
They focus a lot on the HR part, you should prepare yourself well ahead on common competency-based questions.
Anyway, the assessment is divided into 3 parts: the non-technical interview (at least 1 hour, 4-5 competency-based questions, a lot of personal questions, some questions on easyJet), the group exercise (40 minutes, you have to show them how you work in a group) and the sim assessment (40 minutes, I did it on a full motion 737-300 sim, it was awesome!!).
My advice: be yourself and enjoy the day! Smile, ask a lot of questions, show them that you are motivated...
Good luck!
Cristina