Unlike what other people have said, because bittorrent involves the sharing between every bittorrent user, this system is more safe because there are no main uploaders who will be targeted. If the RIAA or MPAA would sue a person, it would have to be at complete random. Like Gary Fung said up there, we have ,"strength in numbers, and security by obscurity.
Many people fret over legal issues and the chances of them getting caught downloading (or uploading) copyrighted material, however, the chances are virtually nil.
Because Bittorrent and all those P2P torrent clients are not connected to a centralized server, there is no way to actively monitor who connects and who doesn't, with the exception of your ISP (however, note that they can only target individuals at a time.).
And malware? Yeah, you get that with some torrents inevitably, but a key thing to downloading a torrent is to ALWAYS check comments (if there are any) on that specific download. People will report whether the download is clean or not. If you read a comment saying the torrent has a trojan, that's usually a sign to back off, however, there are some exceptions (i.e. Anti-virus picks up something as malicious even though it isn't. It happens.).
Now, on the topic of legal issues and uploading, let's say a massive torrenting site is taken down by the RIAA, like The Pirate Bay. They might think "A job well done", however, even though that site is taken down, not only are there hundreds more to suffice for it, but the same uploaders can take THEIR material and re-upload it on a different site!
That's another point I have to bring up. Seeders (I'm assuming you know what this means, but think of it as an uploader if you don't. More on this later...). When you seed a torrent, you are giving out pieces of information for the download to peers, or the people sitting there downloading whatever it is they are downloading. So even if a couple uploaders are sued and jailed, anyone could immediately take their place and it wouldn't matter.
It's quite amazing and complex how far file sharing technology has gotten.
Don't take it the wrong way though; anonymity is extremely hard, if not impossible, to obtain unless you're on a private tracker. A simple DOS command reveals all the current IP addresses coming in and connecting to you. But are they honestly going to sit there and count off the over 300 million users that use P2P, probably gaining new users every day?
Don't think so.
Also, please note the clients themselves aren't illegal, it's what's downloaded, and 99% of the time, it's copyrighted.
My opinion? Copyrights=BS.
d00d sweet!!! i just got microsoft vista from bit torrent for free!
I just downloaded a whole season of South Park from bit torrent! uber cool!!!