Rats really do make wonderful companion pets. They are clean and intelligent. They groom themselves and each other routinely (like a cat) and can usually be trained to use a litter box. Unlike many of the other "pocket pets" they genuinely enjoy interacting with people. They love to play, snuggle, and get attention. They have an extraordinary ability to form emotional bonds with their owners as well as with their cage mates. Rats do not need to be walked, bathed, clipped, or boarded if you take an overnight trip. They don't bark, howl in the dead of night, need vaccinations, or shed all over your house. If you took the best qualities of other pets, rolled them up into a small package, and added fur and a tail then you would have a rat.
And yet, they aren't for everyone. Even though they are not expensive to purchase, rats are by no means "disposable" pets. They require time, interaction, and upkeep. Rats who fall ill need medical attention just as does any other living creature.
Before you decide to acquire your first rats take some time and learn about keeping them as pets. In doing so you will be able to make a responsible decision.