The problems I see with BAT:

1. They will incentivise users to click ads by paying them in tokens. As an advertiser, this is completely wrong incentive and I would not want my visitors clicking, because they get paid. I want them to click, because they are interested in the product itself.

2. I don't see how they will avoid fraudulent clicks. It is already a problem in the advertising industry, but giving payment directly to the user will make this even more of a problem. They claim they will have strong protection in place, but even for Google it took years to develop a proper anti click-fraud protection. They also claim that once user will want to withdraw the tokens they will do AML/KYC. I think this is unreasonable. First of all, the whole point of crypto is that it is not tied to your identity. Secondly, such screening is not scalable and won't make it worthwhile for many people.

3. Some incompetence and poor communication already shown from the BAT team on the early ICO fiasco.

4. Not enough users for the BRAVE browser.

5. Facebook and Google already work very well for advertisers, it would take a lot for them to switch.

I'm writing this as an advertiser and person working in marketing myself.