So let me first off say that I have tried other "list" apps, especially for groceries. None of them even compare to this one. I like to have my list in the same order as I shop, and this app not only lets me customize the categories, but it automatically sorts where each item should go. AND, if for some reason I want it somewhere else on the list, I can move it no problem. But by far the best part of this app is the recipe feature. (I used the free version for about a day before I fell in love and had to upgrade so I could use this) Say you find a recipe you like. Not only can you save it to this app for reference later (and also organize the recipes into different catalogues I might add...) but it automatically imports the ingredients and you can just click which ones you want to add to your list, or all of them.
You can easily share lists, customize the look/feel of it them, make different lists for different tasks/items, etc.
Basically, this is the app you didnt know you wanted, but now you cant live without it.