I used to grit my teeth and use them, but Oracle's behavior in the Oracle v. Google lawsuit disgusts me, and I don't want to have anything to do with Oracle.  You have to have an Oracle account for the virtualbox forums.

Trying to sort through the alternatives.  I really want usb, rdb, and pxe boot.  But I can live without them for now if I have to.  Virtualbox ran well on systems without svm, or vmx flag, and I'm not ready to upgrade boxes.