I have the 700gph model. They have been working great for the past several months as I try my best to keep fish waste from settling under rocks.
They feel pretty solid but I have heard complaints about some tab breaking easily on the smaller models.
What has happened twice already is.. I guess when I turn them off at night my cichlids decide to take mouthfuls of sand and drop it in where part of the impeller shaft magnet is exposed. That is the only complaint I have about this product- the semi exposed impeller shaft. If that was sealed off, I'd benefit more from that. BUT it may be designed like that for a reason, I don't know. This goes to show that they need to simply have the impeller taken out while under water and flush its housing by fanning water at it with your hand.
Other than that it has only done good in making the water cleaner by keeping detritus suspended!