@aral
Assuming their implementation is solid, I actually see their system as a valid compromise moving forward. If they communicated that to me, and if I am using firefox, I probably will turn it on.
However, the problem is that they never communicated this feature, which do require data collection about ad campaign, and just silently turning it on for all users.
When they are caught, they proceed to insult their user by saying, yeah, you don't like it just because you don't understand it. Even though they spend zero seconds educating their user about it, and communicating what does it do.
Although, I do appreciate they call it what it is "ad analytics", instead of google just slap on a random pretty name, like "privacy sandbox" for their analytics.