I found that this was my most stressful interview by far, but some people didn't think it was too bad. The manual dexterity part wasn't horrible, I was just kind of nervous because I had know idea how I was going to do on it. In the end, everyone in our interview group did about the same...no one was incredibly good or really bad.
The group presentation was them watching you work in a group and seeing how you interact with others and present it. There's no way to really prepare for it other than to be yourself and pretend no one's watching you.
There's just one interview, and that was the worst part. I didn't like how there were three people, it made it awkward to try and answer questions to and ask questions to all three of them at once...especially since I was in the middle of the table and they were at both ends so I had to keep looking one way and then the other way, back and forth. The questions they asked were kind of confusingly worded (I thought) or they were just things I didn't know the answer to. At one point they asked me what I would do in a certain situation and they kept expounding on it "but what if this happened...but what about this....but what about this?" Finally I just said, "I don't know, what would YOU do?" haha.
That being said, the school is awesome and despite their interview process I would love to go there. It's worth enduring a tough interview for a shot at an awesome education.