I picked up one of these simply to try single pour over vs other single serve options or using a French Press as it is a very economically priced unit. After spending some time with it since single pour over have become my go to brewing method with a notable increase/change in flavour. #2 cone filters fit well, however I am also using other sizes with some strategic folding no problem. Wetting the filter inside the cone helps keep it in place till you have the coffee grounds and water flowing.
I own three of these now and have had no issues whatsoever. Cleaning is a bit difficult due to the ridges but a small brush solves that and due to the paper filters any residue does not build up too quickly. However it is much simpler and quicker to clean than a French Press. Also they are top rack dishwasher safe and that works too.
I recommend checking out a quick video on using a pour over if you have not done so, but generally it is a simple process.