Forget TripAdvisor one needs PhDAdvisor.com
The relationship between student and advisor is key. It will be long, minimum of 3 years, up to a lifetime, but in Europe, often 5 years or more, so be careful.
Of course the same goes for the advisors, but someone else can write this and get lots of feedback from their asteemed (clever) colleagues.
Ian: This is about Ph.D process from the student side (check with student unions around) the world.
MySlides for staffan