I, too, have had mixed results with the HF blades. They do seem to dull fairly quickly, and it's hard to get them apart when I take them out of the package, as well as the problem with them sticking to the cardboard. And, I've had nicks and dull spots with them. That being said, they are inexpensive, for sure. DH bought me 20 packages one year for Mother's Day and I'm trying to use them, but it gets old having to change the blade so often. I'm thinking there's a reason the name brand, made for quilting, blades are more expensive!
I am wondering, however, about the benefit of buying a blade sharpener. Would it pay for itself down the line if I use the HF blades and sharpen them? Gonna have to look into and think about that.
It's interesting to read the comments - seems people either love them or hate them, not much in between!