I've been using one this winter, and for me there have been some real pluses as well as real minuses.
Pluses:
Ease of use. It goes in a bucket and stores by the back door, unlike the big hose, which has to be dragged out of the basement. Bled or not, the big one freezes if not stored inside.
Very compact. It fits in a bucket. My big hose doesn't fit in anything; it has to be dragged.
Mine came with a toggle at the business end so I can shut it off without turning off the hydrant. Nice for filling individual buckets in the barn.
Minuses:
Dang thing takes 40 minutes to fill my stock tank! My big black hose takes less than fifteen. Mine has a very skinny diameter.
The business ends are made of plastic. Plastic! Not brass, not steel, plastic. It's so much easier to screw crooked on to frosty hydrant threads and strip, or spray the wall and yourself when you find out you didn't get it seated as well as you thought.
The tag on mine said DO NOT DRINK FROM THIS HOSE. Really? Who doesn't drink out of their hose from time to time??? My critters do, every single time, though indirectly. But then I saw the packaging of my big black hose, and it said DO NOT DRINK FROM THIS HOSE.
Mine was a gift. I think I'd always have one on hand for winter use. But for every other time of year, I really like the speed and delivery rate of my big black hoses. Besides, all the fittings are brass, I have an additional brass toggle on the end to turn on and off at point of use, and it's ready to take years of hard work. The little inflatable ones, well, a few winters is all I'll likely see with them before replacement.