My mom and I bought one along with the Bias Tape Maker last year when they were on sale Buy one, get one free. If you can return the cutter I would return it. We were not happy at all and no matter how many different things we tried we never could get a straight cut.
However, the Bias Tape Maker has worked out much better. We bought the 2.5" attachment and use it to make quilt binding. It saves a lot of time because you don't have to fold it over and press by hand. No more burnt fingers! It isn't perfect, but it works well.
I just don't think the cutter is worth the money, though.