The best things about CalTech are the size of the campus (very few students for a school with both graduate and undergraduate programs), one of the best engineering educations I have seen and the great reputation it has all over the world. I would definitely go there again and I am actually planning to do graduate studies there after I finish my undergrad studies. And if I were hiring employees, I would definitely hire students from there.
The worst thing about Caltech is also it's strenght- the fact that it is too much foucused on the engineering sciences. Ofcouse you cannot expect a engineering institute to have the same scope as a liberal arts college but i feel that caltech lacks in breadth of there education even compared to other tech schools like MIT or Carnegie Mellon. So, my advise to high school students thinking of going there is that they should go there only if they are solely interested and focused on engineering.