There really doesn't seem to be anything wrong with this.

It's very simply constructed, there are very few parts. The impeller and rotor is integrated into the siphon tube and drops down into the impeller coil assembly.

The basket is quite large - you can easily cram extra filter material in there.

The cartridges are simple and easy to take apart (to remove carbon, for example).

I haven't had it clog, it doesn't run hot, it's silent. Flow appears to be adequate, it bowls my little guppies over if they wander past the discharge!

It got a little noisy twice when I got a bacteria bloom in the aquarium. I simply lifted the siphon tube and cleaned the gunk off the impeller rotor with a Q-tip. It's been totally silent since.

I'm quite happy with mine (TF20), as a newbie it's easy to clean and easy to regulate the flow. I have used other brand cartridges (Bio-Bag) and they work fine.

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Peggy

20 g FW. 3 Tetras (F), 3 Platys (F), 1 Black Balloon Molly (M), 3 B/White Dalmat. Mollies (F) and a 2" Adonis Pleco, 4" Black Ghost Knifefish and 2 Zebra Snails
HOB: Topfin20 and AC20
Aquascape: Net Breeder for Frys (currently), Assorted Silk/Plastic Plants; Wood, stone and 2 Ornaments for hiding.

I'm going to have to vote this one down based on some recent bad experience and also after getting an AquaClear 20, which puts this one to shame.

I was trying to keep the filter cartridges clean, but it was a losing battle, I couldn't clear the filters simply by rinsing them in aquarium water. It didn't take long before the reduced filter flow caused the water to pile up behind the restricted filter cartridge, spilling over the intake tube back into the tank. Debris started building up in my gravel, then I lost two fish due to mysterious bacterial infections, plus there was an outbreak of fin rot.

Thankfully I had a Top Fin "BIO 3" filter cartridge - I used the reusable blue sponge portion inside the original filter cartridge, discarding the old activated carbon. I just assembled a new BIO 3 filter cartridge using the old blue sponge and the new floss packet. The tank didn't cycle - obviously the blue sponge contained enough bacteria.

But now the "new" filter cartridge is clogged again, it only took a few weeks, and rinsing is not helping.

Save your money and get an AquaClear. Use this one only as a backup. And make sure you use BIO 3 filter cartridges with this, putting an old filter cartridge behind a new one completely cripples this filter.