Windows 9's new Start menu demonstrated on video(theverge.com)
theverge.com
Windows 9's new Start menu demonstrated on video
http://www.theverge.com/2014/9/12/6139255/windows-9-video-demo-features-start-menu
http://www.theverge.com/2014/9/12/6139255/windows-9-video-demo-features-start-menu
Phone: Here is a surface, arrange and size your tiles as you like, anywhere in available space.
Desktop: Here are groups, size your tiles and we'll auto arrange them in sequence in the group they are placed in.
You can be a touch more creative with the windows phone variant; and the experience is more intuitive when you're shuffling your tiles around.
Then again, the windows phone start screen does not react to screen orientation changes, meaning the surface you place your tiles on will never change size or orientation. I can see how the concept of groups answer the "how do we arrange to fill screen when orientation changes without bothering the user too much" question quite neatly; but I hope another few meetings around the drawing board on this issue can produce a more personal experience (rather than the current compromise).
I'd be happy to enable an option to have more customization options, even if it meant laying my tiles out twice (once for portrait, once for landscape).
I hope they don't do away with the start screen completely; I've gotten used to it and rather like it. Operating a surface taught me it's value.