I had an off-site interview experience with Amazon a few years ago, they came over from the US/Canada to London and held a hiring event in a hotel.

You got put in a room and went through 4 face to face interviews which were very gruelling, but the interviewers were nice and positive (although to my British sensibility, maybe _too_ positive!)

I didn't get an offer, I don't think I have the chops to pass the interviews really, I found the preceding 2-3 weeks of interview prep very stressful and time consuming. It's not just the algorithms and data structures bit you have to revise on, you need to think up many anecdotes that align to The Leadership Principles. They're all over that stuff, you cannot be a follower you must demonstrate Leadership.

All in all though I appreciated the experience, I don't think I would apply again though.