I recently treated myself to a Martelli cutter and 10 blades during their 50% off sale. As someone above mentioned, the cutter tends to veer off to the right at the end of a long cut. I have no idea why, have never had that happen with my other cutters. I'm disappointed in the blades. I'm on the second one (don't use it that often) and again there's a "bad spot" on the blade and I have to keep going over the areas where it hits.
I have several cutters and just checked the one I most often reach for. It has no identification, the only thing it says is "made in Korea". I've had it for years and don't remember where I got it. It's the most comfortable and dependable to use (and I have good luck with the Harbor Freight blades).