I am learning a lot in the meetings, especially the summer symposium. It gives you a bird's eye view of latest research happening in various fields of biology. Depending on the person, this could inspire a person to be scientifically better.
It has beautiful surroundings and you get to meet some of the leaders and top scientists in biology today.
Cons
Research environment, ethics, quality and output entirely depends on individual labs and it varies a lot (it could be amazing to mediocre/disappointing). Interested scientists should inquire thoroughly about the specific lab before they join.
Good scenery and good meetings that one can attend for free as a student
Cons
Students are treated much worse than even menial workers at CSHL. It is a great place to be a PI, but a really bad place to be a student. Very poor environment for learning scientists.