I was nervous based on the reviews on this page, but I ordered an inexpensive color ink cartridge for my HP Photosmart C5280 just to try these guys out. I figured the risk was low for the price. The cartridge arrived and didn't work. The printer didn't even recognize it. So I got in touch with them through their contact page and they very quickly sent a replacement cartridge which is happily printing away in my printer. Not the best start, but they certainly stood behind their 100% satisfaction guarantee. I will probably buy from them in the future.
You tend to see mostly negative reviews at sites like this. Happy people just aren't motivated to submit reviews (unless they're shills) like unhappy people are. I wanted to reverse that trend. I'm mostly happy and I'll say so.