Funnily enough - the primary function of a toaster is to toast bread. For people who enjoy toasted bread then it is the ideal piece of technology to use. It is considerably safer than a fire and toasts the bread better too.
An advantage of using a toaster is that you can choose the settings of the toaster and predetermine just how well you want your toast to be toasted. That way, the toaster can cater for everyone's individual tastes.
Another advantage of the toaster is that it toasts quickly and efficiently. Of course - this depends on the quality of the toaster that you own, but in common terms a toaster can toast bread in a short amount of time and will toast the bread through thoroughly.
Perhaps a minor inconvenience is that a toaster users electricity in order to function. That means that you will be paying for the electricity that the toaster uses and this could marginally increase the cost of your electricity bills.
Maybe a greater disadvantage is that that the toaster could be dangerous if it is not used correctly. Users could accidentally electrocute or burn themselves if they are not interacting with the toaster in a safe and correct manner.