I bought it and also bought an Aquaclear 20 immediately to replace the filter.
Since then, however, I purchased a separate 5.5 gallon as a quarantine tank and put the topfin filter on it. I ditched the filter media that came with it; instead I'm using a piece of Fluval sponge, and some biomass in mesh bags that came from two different cycled tanks. I think the theory was good, but unfortunately, the QT isn't cycled.
The filter itself is fine -- quieter than I thought it would be. It's larger than the Aquaclear 20 though.