Well, the Internet does not strictly require all traffic between two parties to go through a MegaCo Cloud. Location privacy in this system would appear to be greatly enhanced (vs Apple-as-an-adversary) if A and B communicated directly, or through a server that they controlled, instead of through iCloud. In concise security terms, Apple man-in-the-middles the encrypted traffic in this system and thus may perform traffic analysis, deanonymization-via-inference, etc as I said above.
It's certainly true that NAT, firewalls, and a lot of other things make direct communication between two iDevices inconvienent and frequently impossible - that's fine and fair enough. But then the Company should not be making at least partially untrue privacy and anonymity claims that are essentially impossible to satisfy when by design all of the traffic flows through their cloud.
AFAICT Apple (and likely its host governments) will still need to be trusted parties in any scheme that flows through their infra, unless you care only about protecting your precise location, and are willing to expose your coarse location to them.
To be clear, they may already have that info from other services, and you'll have to trust Apple a lot anyway since they're making the phone and some custom silicon within it. And them having coarse location is certainly preferable to them having precise location data - so this system (as we are inferring it to work) is not worthless, and is still an improvement over a naive implementation.
But real internet anonymity and location privacy is hard to achieve; just ask any tor developer. So please don't let the marketing dept openly claim that, or even imply that, when the claim can't realistically survive a two minute security audit by HN infosec nerds. To be specific the WWDC claims that "this whole interaction is ... anonymous" and "there’s no need to worry about your ... privacy" are what I am taking some issue with here.