They're really good for curvy items. I even put them through the points of the lace.
The key to a nicely curved crescent shawl is to increase 6 stitches every 2 rows. If you only do 4 sts every 2 rows (or 2 per row) you get a nice trianglar-shaped shawl. The extra 2 sts every two rows creates enough extra fabric for the curve.
Also, instead of starting with a small garter stitch tab at the centre back, I knit a long one before turning it on its side to pick up sts for the stocking stitch area. This avoids a strange point in the middle of the centre back. This is where I got the idea to do this.