Thanks!! They are adorable, no doubt.
As for are they hard to keep? No.
Do they smell? Not really, as long as their enclosure is clean. Most that you will buy are already neutered and have had their scent glands removed.
They do require daily work though. They have an extremely high metabolism, and they eat and drink often. What goes in, must come out. They poop a lot, and pee a lot too, but more poop. So their enclosures need daily spot cleaning, blankets etc...need to be washed often.
They sleep about 14-18 hours a day, but are extremely energetic when not sleeping. They are tons of fun to play with!!! They love human interaction and require a good amount of exercise. So coming out to play for a wile should be done every day, or almost at least.
I've had them for about 2 years now and adore them.
But, would I do it again? I honestly don't know. I wish I had ferrets when I was younger, that's for sure. But I'm almost 40 and enjoy more relaxed pets at this point in my life (SNAKES). I hope mine all live long lives (expectancy is 7 years or so) but 5 years from now I won't be getting more. Once mine cross the rainbow bridge they will be missed dearly, but not replaced.
Hope this helps. If you have more questions I'm happy to help where I can.