The Twenty Fifteen theme is officially posted and awaiting the community’s help to review! Read the official announcement here.
The first time I saw the screenshot for Twenty Fifteen, I immediately thought of the Flat theme. At the moment, Flat is what I’m using here on BinaryTemplar and one of the things that appealed to me about the theme was how simplistic it was. Nothing fancy, nothing too big and bulky, just a clean responsive theme that doesn’t get in the way. Twenty Fifteen looks like it’s going to be going that direction as well, which is a bit of a departure from the media-centric “newspaper” style Twenty Fourteen theme we got last year.
WordPress Trac is already blowing up with suggestions for enhancements and improvements, including one posted by yours truly which I submitted after noticing the issue when working on a brand new site install that I was experimenting with. But it’s all good stuff. With about two months to the release of WordPress 4.1 (currently slated to release the week of December 8th, 2014), there’s still plenty of time for the community to bring this theme up to a very solid polish in time for its official launch.