I didn't think it was difficult. I started by sewing two triangles together, then sewing those into rows, then sewing the rows together. I didn't have the pattern like the Triangle Stash pattern, so I put the little triangles in there randomly.
My quilt wasn't quite random though, I wanted the dark triangles to point upwards to make it kind of "mountain" like.
But I didn't find the piecing hard. Just make sure that you have the pieces together correctly and that the dog ears are where they are supposed to be, otherwise, you won't have enough seam allowance and you'll chop off the points of the triangles when you put the rows together.