There are many different components to P2P systems, but their main use is for the sharing of files. With this comes some advantages as well as disadvantages.
The Advantages
The primary benefit of a P2P system is saving money. Many people have access to P2P systems that are free. So, the first saving comes in not having to pay for the software that is needed to run a P2P system.
For some, there are indirect savings, and this may be more prevalent when a P2P system is being used illegally. For example, instead of someone having to buy their favorite CD, they can just obtain it from others within the P2P network. Of course, legitimate businesses may also save money through the sheer cost-effectiveness of transferring files via P2P.
Looking at P2P systems purely from a legal point of view, using P2P for filing sharing is easy, fast, and efficient.
The Disadvantages
Legal issues are always a concern that comes with P2P systems and usage. Unfortunately, P2P has been used on a huge scale for illegal purposes such as downloading of copyrighted materials. Such practices have a detrimental effect on artists who are being robbed of their royalties because of unpaid, unauthorized downloads.
There are personal risks involved with using P2P software, too. Those that intend to use P2P systems may be at risk of having their computers infected with spyware and malware. Many of the free-to-use P2P systems are cloaked with codes that allow for this. The user has to be very diligent about researching and choosing a trustworthy P2P system.