I wasnt going to bother with this app since I already have another yarn usage app. But this little app is quite nice. I like that you can adjust the gauge and the yardage appears on the screen without having to hit submit. This way you can play with gauge and easily see the yardage without any back-and-forth.
Yardage for sweaters (for example) ranges a lot depending on stitch pattern, cables, necklines etc. The yardage given gives just a 10% buffer (I think thats what the app description said), so keep those design decisions in mind when considering yardage requirements. I thought it would be nice to have the app consider some of those factors, but where to draw the line? I realize its a slippery slope.
Overall, this is a very nice app for knitters, well worth the cost.
Knittingwithwords about Knit Handy, v1.0