If it's safe depends on what you do with it.
I haven't heard of any serious security flaws in any BitTorrent Client, but then there are a lot out there, clients that is. If your just downloading linuxs distros or patches for WoW (using BitTorrent to distribute patches in WoW was pure brilliance on Blizzards side) you should be safe.
Just because it's BitTorrent doesn't make the content safe. Just because the name is "Homevideo of whales" doesn't mean it isn't loaded with spyware and viruses, in fact, as Paperghost pointed out
you can't get buried in spyware from harmless looking torrents.
And if you're wondering if MPAA won't find out what your downloading your out of luck. Not only can anyone who bothers to look find out exactly what your uploading and downloading, but your practically shouting it out over the net.