Let me start by saying I HATE DUST!
All of these air cleaners work pretty much the same, they have a squirrel cage fan that pull air through one end through 2 or 3 filters and blows the "clean air" out the other end. They work BUT unless you are collecting/controlling the dust at the source you will still have a dust problem in the shop. I have one that runs all day and for about 2 hours after I close the shop for the day and a smaller one that I run behind my pen lathe when I am sanding in addition to two dust collectors with aftermarket 1 micron woven filters hooked up to the table saw, band saws and jointer and drum sander and a vacuum with a HEPA filter for my smaller sanders and tools when I am doing flat work but there is still plenty of fine dust around the shop.
For example if you are sanding and do not have a dust collection attachment on your sander the dust produced settles around your immediate work area, eventually some of the settled dust will be disturbed and displaced; some will become airborne and hopefully make it to the air cleaner intake side but most is just going to move and relocate around the work area. As you walk around and if you have a fan going and with the turbulence created by the air cleaner itself the dust that was not collected at the source will move around the shop and resettle so eventually you will have the dreaded layer of fine dust everywhere.
Don't get me wrong the air cleaners do collect some of the fine dust and makes the air a bit cleaner than if you didn't have one but on its own it will not give you a dust-free shop. So, if you want a cleaner shop the key is to collect the dust as close to the source as possible, clean up the area you are working at before you move on to the next one and let the air cleaner take care of the airborne dust you cannot see but is floating around.