Bonus if the "updates" (ads) were targeted to me. If I were vegetarian, it should know not to show me about prime rib, for instance. If it sees I only buy granola or mainly health foods, don't give me ads about lucky charms. and not 30 second commercials either, just quick intros, with video/pictures, and a few facts about relevant products.
Actually, that just occurred to me, if you included recipes with the advertising, that wouldn't bother me at all. Just like reddit's DIY, start with the finished "product", then say " to make this, buy these things" (of course with a shortcut to just add them all to your cart) "and do this:" (cue to video of person making the dish).
but back to advertising, just quick (15s) videos with simple information and price. maybe with sideways scrolling so if I'm looking at margarine, it also has quick links to butter and vegetable oil. Don't skimp on video: each product has the same demo video/advertisement so I can compare them.