Ferrets can be kept in cages for part of the day, but need not only time to run, but mental stimulation, games, and interaction. Particularly later in life, some will develop illnesses that take time on the owner's part to treat. If finding a missed litterbox from time to time, having your socks or underwear disappear under the couch, or having to pluck your pet out of the trash will bother you greatly, then a ferret is not for you. Ferrets can get along well with cats and dogs, and occasionally other animals. Cats may or may not like the ferrets.
Dogs run a higher risk, especially in hunting breeds, of killing a ferret.
Ferrets are predatory themselves, so small mammals, reptiles, and birds are at risk in a household with ferrets. Most ferrets can learn to get along well with other ferrets, but there will be occasional conflicts, and occasionally a ferret, particularly if you adopt an older one from a shelter, who will refuse to get along with others. Both ferrets and children are naturally inquisitive and playful and both if over excited can be unintentionally rough. Some shelters will not adopt to households with infants or small children as a rule, to prevent a potential problem, and many will not adopt to a household where the primary caregiver of the ferret is a child. Many ferrets end up in shelters because they were gotten as a pet for the children who tired of them, or became busy with othe childhood things, or grew up and moved off to college and couldn't take the ferret with, and the parents were not willing to care for the animal.