Up and running here. Mostly seems to be working fine, don't have any issues with the Home key or anything like that. Not seeing apps like Chrome get multiple "Recents" entries though. I thought that was in this release? Perhaps Chrome needs to get updated for this to work.
The individual tabs in recents might not even work on the next beta, as the leaked screenshots of M37 on L still showed the tab switcher in the Chrome action bar. I get the feeling that a lot of what they showed were just mock-ups.
One thing you might be able to see: During the fireside chat they mentioned that when an app gets opened from within another app it will no longer take over the parent app's recents entry, but get its own separate one. An example of a current problem like this is opening an email link from Chrome in Gmail. It won't let you switch back to Chrome through recents, you have to back out of the compose message screen.
Could you check if it now works as they promise? I'd also be curious whether the Gmail compose message entry appears separate from the main Gmail activity if you already had it open at your inbox.