Hi, all. I am starting a PhD (tomorrow!) and am getting nervous. I just completed my MSc at the same school with the same supervisor. We have a great working relationship, but as she is a new prof, she lacks the experience and wisdom of a more established prof, and I actually starting to doubt how much she will be able to guide me once I get into it. What do you folks think are the most important qualities of a supervisor?

that they have time for YOU and that the topic you are going to be working on is of interest to them.

Are you in the UK? A prof in the UK would be very experienced. I did read that a younger supervisor can be better than a more experienced busy supervisor (like mine who you can never find) as they have a lot more time for you.
Getting work back quickly would be a nice quality for my supervisor, but failing that I did eventually got very detailed feedback.
You can get advice from other people to widen your knowledge, e.g. your peers, postdocs and other people experienced in a particular area.

CC, I'm not in the UK, and my supervisor is not a prof (in the UK/EU sense). I'm in Canada, and here we tend to call everyone 'professors'. My supervisor started two years ago, she's an assistant professor.