Just downloaded the GM on my 3rd computer an older MacBook Air. I just thought Siri would be a gimmick. But I have to say Siri on the Mac works great!! It feels right at home on the Mac platform. And actually makes a lot of tasks a lot faster than using keyboard shortcuts / mouse. Searching is really fun and satisfying. It's definitely faster than iOS. Saying things like Show me images of Dogs. Shows all the images in my library of dogs instantly. It's really snappy even on this older machine a 2013 MacBook Air. Can't wait to install the final release on my iMac! What are you guys impressions?