There is a learning curve with the Martelli cutter. It really helped me to watch the youtube video that explained the way to hold it properly. Stick with it if it feels awkward at the outset, because you'll get the hang of it, and it's a much less stressful way to cut.
The Martelli blade has a circle in the center, rather than a notched circle like the Olfa and other blades. You can use other blades with the cutter, but the notches will eventually damage the bolt, and you'll have to replace it.