C.M.
Myself and my 3 siblings are all graduates of NSCDS. It's a wonderful school! My brother, the youngest, had the benefit of attending their lower school, while the rest of us attended middle and high school there. The lower school is amazing, and really provides the necessary foundation for a lifetime of learning. He had the benefit of picking up excellent study skills and life long friendships. (He's now 28 and still very close with his NSCDS buddies) The teachers are excellent. They are not the highest paid (the public school teachers in Winnetka get more) so they are really there as they love teaching and the school.
I loved NSCDS because I feel it made me a very well rounded person. Because of it's smaller size, I was able to be on the Basketball, Field Hockey and tennis team even though I am not a great athlete. I also got to be in several dramatic productions and art shows, though not an actress or artist. So I got exposure to many things, which has only benefited me as an adult. Also, my friends were from all over Chicagoland. I had friends on scholarship who took a train every morning from the South side, exchange students from China and Australia, kids from the city and the western suburbs. So it was not as homogeneous as some other schools on the North Shore.
Now as a parent of a toddler I hope to be able to send my son to NSCDS and get the benefits of a small school. Many of my NSCDS friends now send their kids to school there too. If you can afford it, it's definitely worth it!
Good luck, and feel free to email me with any questions.