The yarn makes it, of course, or it would look like nothing on earth. The thick-and-thin nature of the yarn means the edges are very irregular so I used an overcast seam. I also worked double crochet round the neckline and armholes, which neatened it and built up the shoulders a little.
The yarn is fun to use and knits up quickly. It's comes up quite bulky so I'd be wary of using it for anything with sleeves unless they were very baggy.