The App Store has one slot at the top of the search listing for a promoted app. This will change to multiple slots.

As an app developer, I used to have to outbid everyone to get the one and only spot. Now I need only outbid the top 3 bidders (or however many slots there are).

I advertised for many months back when App Store ads first started, and it was worth the expense because of higher sales. I no longer advertise because the one and only slot is far outbid what that slot is worth to me, and that I can recoup without spending a lot or raising the price for the app.

So I chose not to advertise and keep the app price lower.