For those who are not in the US, I managed to enable it on macOS by setting three things :

- In General > Language and region : Both Language to English US AND region to US - In Apple Intelligence : Set siri language to English US.

Then you need to reboot your mac. You'll have to apply to a waiting list, in Settings > Apple Intelligence. In my case it only took a few minutes.

Same procedure doesn't work for me on iPad where it says I'm region locked. Even with a VPN. As far as I remember, Apple introduced a pretty efficient daemon in iOS/iPadOS to detect region (for Europe's App Store easing of restrictions) and it's likely what's blocking there.

I'll refrain from too many early comments, but it seems fairly limited.

Asking a question about macOS (How to change DNS) will trigger a AI response that quotes the macOS user guide, while asking the same question about iOS will default to a basic Google Search. Haven't seen any fallback to ChatGPT, that may not be part of that beta.

Mail summarizing looks OK, but fails on some very long emails. When it works, the summary is fairly short (about 3 sentences max) which is probably pretty adequate.