I have ferrets and I absolutely adore them. Out of all the small animals I've kept, they are easily my favorite. Mine are litterbox trained (both in their cage and when they are free in the house - though accidents do happen!), leash trained, and know a handful of tricks each (this week we are learning chase your tail!). They are incredibly smart, and have fantastic personalities. Some people think that they are "smelly" but with a proper diet, and with daily cage cleaning, I actually like how ferrets smell. They have a kind of pleasant scent to them, I think, when they are being properly cared for. They are just they funniest little creatures, and form fantastic bonds, both with you and with each other. Plus they are just adorable. They wrestle and chase and run into things and are just the sweetest. They also travel pretty well (if you're going somewhere that allows ferrets).
But they are definitely not for everyone. They are very high maintenance, and require a lot of attention. It can be frustrating breaking them of bad habits (like digging in their litter box, tearing up their bedding, etc.), and they will often find new ones if they get a little bit bored. They live decent lives. Mine have all lived between 7-10 years. But they are prone to health problems. I have had multiple vet visits with all of my fuzzies.