I can cut about six layers of regular quilting fabric, less if the fabric is of heavier weight but generally about six layers.
I find that it is VERY accurate, it has a strip of foamy, almost like weather stripping (the stuff you use around doors to keep the cold air out) that keeps your cutter/ruler from sliding on the fabric as you cut.
The only thing that I have found that is hard to cut are pieces that are less than an inch wide IF you are trying to use the ruller attached to the cutter. HOWEVER, if you use the lines on your cutting mat to cut I have cut 3/4 inch pieces with no problem!!!