I think this is a more than valid concern, yes. I'll look at that for super-small screens.
On the others, can you post some screenshots on what you're experiencing?
Google highly recommended this and I've been dragging my feet for years on it. Sorry.
It definitely forces me to see it more than the horizontal ones..
Now if those ads are more interesting/applicable to me I would love to click them. Currently it's showing an ad for "Learn Hypnotherapy New Zealand"
Not really my thing..