Its used for downloading files P2P. You have to download the torrent which is really small in size like in KBs and then put it in this software and it will download the whole file.
Utorrent is best in its category so there are hardly any disadvantages.
Yes its recommended for safe and routine usage unless you download infected torrents and download them in your PC. Then also its not utorrent's fault. You can say that in very simple words that its a download manager for torrents.