It works well enough. Wheat seems to be a good material for absorbing and holding heat. It is convenient to microwave and the material is good (like a fleece) and strong.
The size is good for knees and arms. It is also ok for theneck but a little short so it can fall off if you move about with it on.
Lavender smell is pleasant and not overpowering for me (I like the smell of lavender).
My only real issues with it are:
1. There wasn't as much wheat as there should be, so if you put it around your neck, the wheat all falls to the ends and the bit behind the neck has no wheat.
2. It is just a bag with wheat grains in. I would be tempted to make my own next time, maybe using an old bit of material and getting some wheat from a health food shop.