Shared Hosting Pros
1) The cheapest of all paid web hosting options, especially considering the high availability of coupon codes for additional savings.
2) Does not require any maintenance of the server operating system, the web, ftp and mail servers, dynamic language interpreters (php, python, etc), databases and basically any of the essential server-side software.
3) Does not require maintenance of the network, including uptime monitoring, load balancing, basic DDoS protection and general security.
4) Does not require maintenance of the server hardware.
Shared Hosting Cons
1) Very limited CPU and RAM. You are sharing the same hardware with a number (usually a big number) of other users, each allowed to use a portion of the shared hardware resources.
2) Inability to install and use own server-side applications, such as own web, ftp or mail server daemons.
3) Due to the shared nature of the access to CPU and RAM between users – the performance of your site might be affected by other clients.
4) Due to the shared nature of the access to hard drives – there is a possibility to face security issues, even though such possibility is very low on modern web hosting setups.