Persistence is the key issue
I've no idea what the lawyers will do with this case. Probably, make a mess.
However, isn't the key point how long Google retains any sort of memory of what it "learned" by scanning my e-mails? (By which I mean purely statistical analysis thereof. Not forwarding them to the NSA, which is a separate issue, nor storing the actual e-mails after I delete them, which might actually be illegal under EU law).
I've no objection to Google delivering targetted ads based on a statistical profile that is forgotten over a week or two. If they continue to profile me cumulatively over months or (gods forbid) years, it starts to become highly intrusive. Most *people* can't remember in detail what I was doing this time last year, and that's including myself in "most people".
As for the ads, I never see them anyway. Because some advertizers insist on delivering visually intrusive graphics that make me feel nauseous, I block all adverts, and also all flash content.