I like the 'crispness' of the patterns on my EQ7 (computer quilt design software), but I still don't know exactly how it's going to look until I put the actual fabric together with my machine. It even looks different stitched together than when it is pinned to my design wall.
But I do find it helpful to be able to change things around and 'play' with the design before cutting the fabric or taking the first stitch. Saves lots of unsewing! There's enough of that anyway!!!