I went through the new interview process about 3 weeks ago and was quite worried about it beforehand. To my surprise it was fine!
The motivation paper was a multiple choice test on the information NATS should have provided you with. The group exercise was playing a game, quite good fun, then commenting on how well we worked as a group and ways we would improve if we were to do it again. You get no feedback from any of the interviewers about how you've done. There was 5 of us there for the day and we were all fairly similar personality wise, probably stemmed from the original personality questionnaire.
Then came the dreaded computer tests. Not much to say about those, sure you've heard it all before. The interview was mainly HR questions with a few technical questions from an ATCO, who was also present. The interview lasted about 1 1/2 hours.
I don't think you can ever tell how well you do with the HR stuff but if you know the technical part you should be fine. I was, I'm just waiting for my medical now and security clearance before I start college on the !!!!e new wages!
Hope it goes ok.
Jo