Doing PhD with a 'star' professor
I knew somebody who started a PhD with a super-rockstar in Computer Science. He told me he met with his advisor thrice in a year or so, once (a short meeting) when defining the thesis topic, once crossed him in a hallway, and came across him at a conference. It turns out the rockstar was on the road almost 24/7. He changed to a not-so-famous advisor, and was much happier.