FreeNet is an interesting concept, but there's not a lot of "regular" files shared on it yet (that is, movies, software and music).
For secure communications it beats the others in principle because not only are the transmissions encrypted, but the file requests are routed in such a way that nobody else can detirmine who is hosting any file, or who is requesting it. Your ISP can detect that you're running FreeNet, but can't really tell what you are doing with it. Nobody else can accurately detirmine remotely what files you are hosting, and you cannot detirmine who is downloading files from you. And it supports "torrent"-style distribution--on big downloads, your download speeds can regularly go far above any single person's upload speed.
Most of the content on it is "websites", and most of these are "normal" enough opinion/blog type sites that they could be placed on the regular interenet anyway, -but not all. As something of a testament to the level of anonymity, for a long time there were at least two hardcore child-porn sites that show up in both major indexes. If police can't figure out how to stop
that, then it's a good bet that police can't stop anyone else from distributing anything else either. If you want to post material truly anonymously, FreeNet is really the only place I know that you can do it.
The kiddy porn is only two sites and the indexes summarize the sites pretty well, the rest of it is pretty normal stuff. And there are a few files shared. There's one long-standing site where you can download all the Star Wars movies for free, for example.
www.freenetproject.org/~