Product review (4 stars): This filter works. Don't buy the Chinese knockoffs!
As far as comparing this authentic filter to the generic Chinese knockoffs, there is a substantial and measurable purification of the water with this filter. Even when I was told to replace it the filter was still functioning to a level that exceeded that of the crappy Chinese versions. If you want to save money I would just keep this filter in for 2-3 times longer than recommended rather than buying the completely functionless Chinese versions that are cheaper but offer virtually no filtration whatsoever.  When I tested several of my knockoff filters I was blown away when I couldn't get even a difference of 30 in the TDS (total dissolved solids) measurement. I think it was more like 10 or even zero most of the time. I definitely would not waste money on a knockoff filter because you're basically buying something that does almost zero (maybe alters the taste slightly) whereas this filter actually does something. It also feels heavier, which suggests to me that it contains more filtration media, which could explain why it actually filters something versus nothing. This still isn't a great water filter in general, and if you really want the cleanest water you will need to opt for something that doesn't come out of the fridge or connects to the water supply and filters it from there.