They made it so that when you scroll past an ad, instead of actually scrolling past it, it now sticks to the top of your screen taking up the majority of the view and you have to flick it away. Ads come up every couple of posts so it's just way too annoying and intrusive to use, so I've deleted the app. (this coming in at the same time that they've introduce a paid subscription service to remove ads is really telling and might be the final nail in the coffin for tumblr in general)