I've bought the Harbor Freight blades and have never had any trouble with them. I gave one to a quilter friend of mine, over 6 months ago, and she's never had any problems with them either. I have read and heard that the June Tailor cutting mat will dull the blades. This is the cutting mat NOT the June Tailor Shape Cut Ruler.
If anyone has a problem with the HF blades then they should return them, because if there's a problem and no one returns them or complains about them, how is HF supposed to know and to correct the problem?