You know when a great architect draws a chair, and it may even look beautiful but it's the most uncomfortable chair you ever sit on? That happens because he is used to work on a scale where ergonomics is a different thing? This reminds me of that...
Everyone knows Jon Ive is a great product designer, but it looks like he doesn't really understand Interface design. The UI needs his on identity, it can just be a poor child of the Hardware. The UI needs to "Think different" as much as the hardware. This UI is just a bunch of safe choices, from the font, to the flatness, to the icons and colors. It is just disappointing for an Apple user, how is used to slick, subtle, great design, to see this lack of identity on a UI. He didn't won my heart.
And I say this as a graphic designer how tried the Beta.