A mainframe computer is a scaled-up version of a regular computer with increased performance and processing power. They are usually very large and serve many users simultaneously, being more specific to corporate environments. There isn't a clear line between which aspects of mainframe computers can be considered an advantage and which are a disadvantage, as the usage scenarios can vary from one business to another. However, a few facts can help you draw the conclusions for your usage needs.
The physical size and the hardware components of a mainframe computer are different than the ones of a regular computer, making mainframes more complicated to set up. Mainframe computers also need special operating systems and software to be able to take full advantage of their hardware, which complicates the installation process even more. Also, a mainframe is accessed through a terminal, and the installation and configuration of each terminal can take time and money.
One of the most noticeable disadvantages of a mainframe computer is its cost, which is significantly higher than the cost of a regular computer. However, the implementation of a mainframe computer that does the work of several other computers can prove to be a more profitable solution over time in terms of upgradeability, as fewer components will need to be replaced or upgraded to enhance the performance of the mainframe and thus the experience of each user, as opposed to a network of computers where each computer needs to be upgraded individually.
A major advantage of mainframes is that they are very stable compared to other types of computers. This is especially useful in a usage environment where uptime is very important. A hardware problem, however, will affect all the users that work with that mainframe, and can bring all the users to a complete halt.
You can use a mainframe in multiple ways. The users connect to a mainframe with a terminal that has a screen and keyboard, but usually no processing device, relying on the mainframe to do their tasks. You can use a regular computer as a terminal, however, which gives users the ability to process smaller tasks on the computer and use the mainframe for more complex tasks, balancing its use and increasing the number of users that can benefit from its increased processing power.