It wasn't too hard as long as you take your time. I also carefully calibrated my monitor using Profile Prism. It's not photometrically based but I think a perfect score for color judgement makes me confident enough to manually calibrate my monitor using several Prism calibrated printouts. I also calibrated the monitor using diffuse noon day sunlight to light my pictures. And considering how picky I am about printouts I'm not surprised I got the perfect score, I'll nitpick the way Epson printers have a vertical grain and how colors fade from dark areas to colored areas like when you print out the profile target, the area directly next to the dark lines is slightly lighter in print color than in the center of the boxes. I also can fairly easily pick up the very slight color difference between new and old kirkland paper.