Tried it out with a couple recipes this weekend, and this is a really useful tool. Menus are intuitive, the recipes and presentation are very nice, and the section containing general information and helpful tips is really useful. The tutorial videos are also done well.
Some of the nice touches include a calorie indicator, and the ability to rule out ingredients that you're allergic to.
Overall, I like it very much, and will be using it pretty often I think. Probably one of the best uses I've found for the DS so far.