Hi Hillary.
I’ve got 2 copies of the book & the app, the book is great but the app is a lot cheaper & more convenient these days I guess!
Hadn’t updated the app for a while & it used to have problems for me, the biggest was it couldn’t be used offline (or stored on the sd card, I forget which). Because if it couldn’t update the database you couldn’t use it, this seems to be fixed now.
The search/categories are as Annette says, hit & miss till you’re used to them. I haven’t tried it yet but it now let’s you add/edit foods which I think is a big plus as my books are covered in biro!