I've got three of these things, one the later type that has a little hose built onto the brush roll housing. This one I use for clean-up on handy-man type jobs; women don't like a bunch of sawdust or similar left on their floors when you're done.
I've got two of the plastic housing jobs that are a little older, one red and one black. Today, not only my wife was sick in bed, but also my younger daughter. I volunteered to go over to my daughter's home and help her out, take care of her many animals, clean up the house, take out the trash, etc. I don't know who did all this nursing and housework for invalid relatives before I retired. Beware of retirement; people you know look around when they need a victim and see you. They think, "Good ole whatsisname isn't doing anything; let's get him to do it."
Anyway, I took the little black Dirt Devil hand vac to help out. When it came to cleaning up cat litter (sand) around the edges, the Dirt Devil sucked some of it up but the brush roll threw a lot of it around including to the rear where I'd already cleaned. I had to go over these areas all over again with a broom. This was on a hard floor, so I guess it would be okay on a carpeted floor. I won't use it to pick up cat sand again.
The fan in those things is a flat (about 1 CM tall) 4 bladed fan, and in my opinion, it is pathetic for generating enough airflow to clean anything up, that's why I dold mine on and replaced it with a Kirby Vacuette which has a bigger fan with more blades AND is tapered to generate more suction... :)