I've browsed it for ages, as long as you encrypt your traffic well, everything works fine. Even if you're technologically incompetent, the browser can be set up to make sure that very little information about your browsing could be found out, even if you were to go to some of the more "criminal" things on the deep web.
The worst things I've found so far are:
1) Bugchasing sites for gay people who want to be infected with HIV
2) A bestiality story site
However, I did find a site where a bunch of women were swapping adultery stories, which was kind of relieving awkward to view. Essentially, the deep web is like the surface web on crack.