Corporate Finance Summer Analyst (IB)

The whole process was very casual. I had the first round on campus, and a few days later, received an invitation to visit their office in Chicago to do second round interviews. Strangely, they seemed to interview their candidates one at a time over several different days. As such, I was the only one there on the particular day I visited.
The office interview consisted of eight 30-minute interviews and a lunch with 2 analysts. I didn't do a lot of office visits with other banks, but I've heard that eight is a lot. However, if you really fit well with the guys in WB, the interviews should be pretty enjoyable. I didn't have to answer any technical questions, and the guy who asked me some brainteasers was very nice about it and wanted to see if I knew how to explain my thought process. I even got one of the questions wrong the first time around but he guided me through (and I got the offer, still!).
The lunch was also very casual. The analysts who took me out were probably given instructions to see whether I was a jerk, but they were also very nice and honest about what they thought. They were also happy to have some time to eat out.
Since there are 8 interviews, a bit of stamina is required, but if you enjoy their company, it goes by quickly. It's also a good indication that you will fit well with the firm (what they're looking for) and get a good response from them.