We're actually in a unique situation where the planning+buying isn't the hard part, but the deciding is. We're within walking distance of a super-cheap grocery store and I'm able to cook a wide variety of dishes - many of which I can make quickly. The hard part is my wife doesn't do well with open-ended questions like "what would you like to eat"? Seeing a discrete list of things I can make and her just picking/submitting the options would solve the problem.

Though that only holds while we have free time. If we have a kid, then I can see a great amount of value in that app.