I've made a couple of these now and for me the worst part is pressing all the seams open. I hate pressing seams open, but if I don't I get such a knot at the center it's tough to sew and worse to quilt.
Other than that, I find it to be a pretty forgiving pattern and not as difficult as it looks. If you're slightly off it's not really noticeable - there's so much movement and activity in these quilts that any little boo-boos are camouflaged!