Define safe. What is it to you?
Not get busted and sued by police?
Not get virus attacks?
The answer to both is technically, no.
First of all, i am not so sure but dun think there has yet been a
case where someone was caught using p2p illegally and fined.
Although there are some cases of mass distribution of copyrighted
materials online.
Truth is, there is no way the police is going to sit there and
trace ppl who download things. The ISPs are doing it. However, it
is impossible to do effective tracing and keep the cost down. You
need to employ thousands of ppl who sits infront of the computer
all day and trying to find patterns in their customer's received
and sent data every second. Usually it take months and luck just to
catch 1 guy.
Virus attacks? Not so much. But there are plenty of trojans. P2P is
1 of the easiest way for these things to enter your computer.
Softwares like limeware proved to be the most dangerous. As for
torrent clients, it is possible, but so far no problems for me.