So in that regard, what does a page look like with Pi-Hole running? As 'aesthetic' as uBlock? Or does it still show the ad's dimensions - just not the ad?
In my experience I don't notice things being different when I'm using the Pi-Hole. It just seems like regular functional internet. When I'm not connected is when I'm surprised by how many ads there are and where and when they appear.
Probably depends on the underlying CSS, but obviously CSS that comes with the and won't be downloaded, and I generally don't notice massive empty spaces.
I actually use pfblockerng, it does the same thing without the pretty UI.