It's not working very well. How much more data do they need to collect before it starts working?
When you see an ad that's too tailored most people just get scared anyway.
Damned if you do, damned if you don't.
I've seen relevant ads beside search results on Google, but that doesn't really take a lot of magic to figure out that when I search for "Aeropress", I'm interested in coffee.
Ads in podcasts have been somewhat effective as well. I use Blue Apron, I like Audible, I've checked out Squarespace, I bought a Casper dog bed. AFAIK, none of the podcasts know anything about me, but they do know generally who their audience is.
And even with all that, the most of the targeted ads aren't any more compelling than content-based "spray and pay."
IMHO, targeted ads are pointless unless they're a targeted to a search query.