Overall that seems decent as far as privacy is concerned, though there are 2 things I don't like about it.

1. It relies on an 'aggregation service', which you'd better hope is trustworthy because they seemingly get all info about what 'impressions' you had and what 'conversions' you caused.

2. This is the browser acting on behalf of advertisers. It's nice there's a way for people to help companies benchmark their ads, but this really shouldn't be something a user agent does without being explicitly told to.