'Torrenting' or P2P sharing can be a fast way to download software from small companies and developers who have no other way to distribute their software to a wide audience quickly. However torrenting much more widely used for distributing illegal, cracked, hacked and infected software.
Torrenting is something that may have some benefits if you have a particularly fast download speed, which downloads via http and ftp cannot meet, but of course this relies on how many people are leeching and seeding the torrent at anyone time (the more seeders the faster the download). I NEVER USE TORRENTS TO DOWNLOAD ILLEGAL/CRACKED SOFTWARE
and neither should you if you start torrenting.
I generally see torrenting as my last option for downloading software (if I have a very slow download or it the http download has to be recombined once downloaded for it to work properly which is too much hassle for me) A round up of the downsides of torrenting follows:
Constant leaching and seeding, unless you have an SSD, can significantly reduce hard drive life
The speed of your download is totally reliant on others seeding it to you.
It is impossible to tell if a torrent contains a virus until its too late.
Your ISP may lock down torrenting ports to 10kb/s as peek periods. A list of upsides follows this.
Can be the fastest way to download programs from small developers.
Can be an easier way to download large files from developers who have to split the file up into segments to be able to offer it via http or ftp.
I hope this can show you some of the pros and cons of torrenting, there a many more to consider but in my opinion these are all the major ones.
P.S. If you do want to start torrenting I recommend uTorrent (Torrent - a (very) tiny BitTorrent client