I was approached by a recruiter from the company via email, and we arranged a phone call for the following day. Two phone calls with two different recruiters later I agreed to come in for a Super Day at the London office. My impression of the recruiters was positive, they were friendly and professional, and the competency-based questions were fairly straightforward, if a little intense.
The Super Day itself was very 50/50. The initial impression that I got was that it would be a laid-back chat with some competency-based tasks. I wouldn't argue with this evaluation when it came to the first half of my interview. My interviewers were very personable and genuinely nice guys with whom I quite enjoyed chatting. They asked me questions about my previous roles, told me a little about the role I was interviewing for, and then we did a short case study task. The case study wasn't difficult, just required a fair bit of common sense and the interviewers basically helped me through it anyway.
The second half of the interview, however, became much more job-role relevant. It's not that the first half wasn't, but that it had been more about my personality and seeing how my brain worked and how I answered questions. This half was much more intense and became more like sitting in an office with HR while recounting all my worst work stories (have you ever dealt with a difficult colleague? Have you ever had any criticism, and how did you deal with it? Why did you leave your last role? You get the gist). I felt a lot like I was being judged for every tiny little thing - and not in a good, or appropriate, way.
I heard back about the decision within a couple of days, however it was from and HR colleague in the NY office, which, unfortunately, ended up on my phone bill. If I had gotten the job I may not have been as annoyed about that.