I bought one a few years back. It really polishes the water nicely. Problem is that I always end up some blowing diatomaceous earth into the tank (most of it gets filtered back out though). Also the filter bags seem to rip really easily. I even followed manufacturers instructions to extend life of the bags..didn't work. I used it infrequently, and I don't know if the bags got dryrot or what, but they cost about $20 to replace. Hoses were pretty cheap too, tend to kink and collapse somewhat. Unfortunately you can't just replace the hoses...due to some of the placement of the fittings, sturdier hoses just won't fit.
Like I said though, it did polish the water nicely.