Apple launched Search Ads this week and Lukáš is quickly on board with a nice rundown. He's going to keep updating this post as he learns more, so it's a great place to start. Whether you like that Apple is showing ads in the App Store or not, you need to experiment and see if you can increase your downloads without breaking the bank.
Apple is currently offering a $100 credit towards search ads just by signing up. As long as you aren't advertising against any of my apps, I say go for it! ;)
Experimenting with App Store Search Ads by Lukáš Petr