There was a technical test, 2 to 1 interview with competency questions and a group exercise. The test was doable, and it changed based on the role you applied to. The interview was fine, the two people interviewing me were friendly and interested in my projects. The group exercise was quite pointless as there were many people discussing an uninteresting topic.
They provided feedback on the phone after a few weeks, but it was given by someone else which was only reading a scoring sheet, so wasn't able to actually explain what was good and what was bad.
Also, they limited the expenses reimbursement even though the interview took place in the centre of London early in the morning, therefore required accommodation the night before. The day was quite long, with a lot of empty moments in which we didn't have much to do apart from waiting for the next step.