At first I attended their code for good contest and got the prize. One week later, they offered me onsite interviews in London. The interviews includes code interview, technical interview, competency based interview and a group discussion.
The problems are not tough indeed. No coding, no brain teasers, but I was not prepared. And it was quite stressful to have 4 interviews in 4 hours. I think what they concern is not the coding ability, but the teamwork. By the way, a interviewer keep shaking his legs all through the interview, which is a bit annoying.
It toke 4 days for the HR's response. The HR call me by phone and gave me the feedback.