It did nothing for ad tech crap yet, but it gives you many easily exercised rights to access and erase your data. An American company "OpenAI" has released a very useful human-EU bureaucrat-translation tool for drafting such requests.

I'd argue that it actually did one good thing regarding ad tech: I've seen many people - who generally aren't interested in privacy, or politics in general - being very surprised by the number of companies their data is being sold to.

For someone who isn't aware of the scale, seeing "we sell your data to >1000 companies" can be enough to build interest in advocating for privacy laws.