Not noticing anything useful of Proactive or Siri suggestions.
(1) Recent contacts seems to be the same as the app switcher of iOS 8.
(2) Suggested apps are always the ones I’ve been using in the past minutes.
(3) It suggests me news articles of websites I’m absolutely not interested in.
(4) Nearby Spotlight searches only available in the US and China, apparently.
(5) Proactive only works with Music, and only when I plug in my headphones or connect to Bluetooth (Apple said that it was location-dependent as well, but I found that to be not true. It will always suggest the Music app to me when I plug in my headphones).
For the rest I haven’t noticed anything of Proactive during the beta until now (with restores in between), nothing whatsoever. Such a disappointment.