The ability for me as an individual user is that I can easily add candidates with information from LinkedIn or other sites so they are in my system instantly! I also love how easy it was to create new profiles of potential employees using pictures taken by myself (or others) instead of having them take time out of their day to do this themselves.
There isn't much at all but problems when trying to find someone who has done similar work before which you use. You have no way of knowing whether or not they actually did something like yours previously unless you ask directly. This works great if you already know where to look online because you just simply search through websites until you come across one person looking exactly like yourself.