I assume you are referring to these things:
http://www.amazon.com/Swim-Time-NA316-L ... B000MOIX3A
I have one and it works very well. At spring opening this year I had a fair amount of smallish tree seed/pods to clear up from the bottom. No way I could do that easily with a leaf rake. especially through the haze. The 'bagger' whipped those up in no time. Obviously the mesh is not small enough to retain fine stuff which gets blown up in a cloud, but that usually settles quickly for vacuuming.
The only 'pain' really is having to hook up to a hose. Mine just came with a female hose connection, so I fitted a quick hose connect. When lifting the 'bagger' out of the pool you have to invert it so that the bag contents do not spill out, so you might get sprayed a little, unless you fit an inline stop-cock. Best also not to fill the (string-draw) bag too much at a time as it might slip off the base under the weight when inverted.
If it is the type that runs on little ball wheels you might also want to check that they are smooth. Mine had a few burrs that I rubbed down. Don't want to damage the liner.
So, yes, if you don't want to spend the bucks on an automated gizmo, I think they are well worth it.