Many reasons- I think my peers are smarter and often more interesting than the average student at a state school.There are only 4000 undergraduates and 95% of us live on campus, which makes for a very close knit community. Professor are very good, and since classes are so small, they often take student out to lunch or invite them to their houses for dinner. We have excellent resources-- kinase pro is right when he says that DMS is a mid tier med school, but this simply means that dartmouth spends most of its money on facilities to be used by undergraduates.
rednawz was describing the 6 month waiting period before you can volunteer at hospitals near berekeley. With a small premed population, I was able to work many volunteer positions at DHMC with no waiting period/red tape. Also, I took classes taught by research profs at DHMC and DMS, so just by approaching them after class, I was able to get two research positions in material that I found genuinely interesting.
Finally, with a 9:1 student to faculty ratio, you really spend a lot of time with profs, which make for great letters of recommendation. Also, there is never a line to see the premed advisor. Finally, since DHMC is a major medical center, finding doctors to shadow took no effort whatsoever.
ANd then i hear horror stories like what boxinmoxin is experiencing at his commuter school, so I think it is safe to say that the small, private, elite college experience is indeed unique
