I had bought a similar one (designed for scrapbooking) that was on clearance...found that it would not cut fabric at all. I'm thinking that the only way that type of cutter would work is if it had a rotary cutter type blade and very firm clamping down on the fabric.
We had a rotary blade paper cutter where I used to work and it only worked well on multiple layers of cardstock if the bar was clamped down.