So Microsoft will introduce its own tablet, the Surface. They deliver one very nice touch for it: the cover with an integrated touch keyboard, which includes a touchpad. This will make the dual use they envision much more practical, by significantly reducing the weight of the entire tablet. But as already discussed, the whole premise is a pretty flaky one: Software can only be optimized for one use case, and so the device is actually two in one: laptop and tablet. As a laptop, you will get a much better experience with an 11″ Air than with the ARM variant. On the other hand:
The ARM variant is the only one usable as a tablet, as the other is too heavy. And both will only sport a 140 dpi screen. The Retina display on the new iPad is actually amazing, as it suddenly enables you to read a full page of a document comfortably. You simply cannot compete against the iPad with such an inferior screen, especially if you want to capture a professional audience, where being able to read crisp text makes your life so much easier.
Microsoft seems not to understand that computing has become cheap, that you no longer spend 5000$ for a somewhat reasonable machine, but that 1000$ can buy you a computer that is overpowered for many and considered high end. With so much power available cheaply, it suddenly becomes quite economically possible to own two specialized devices, each working optimally for its use case. And Apple is working very hard to ensure that iCloud will work seamlessly to make working on multiple devices a joy.
In the end, Metro software does not work nicely with keyboard and mouse, and Windows software does not work nicely with only a touch screen. To make the switching work really well, one would need to develop every software with two different faces, and the hardware would be the wrong for one of them: either too underpowered for keyboard and mice, or too heavy for touch. The first one will go away with time, but Microsoft is actively preventing people from developing ARM desktop applications.
Of course Microsoft tries to leverage its position with Windows to get traction with tablets, but that means an inferior product user interface wise, and Apple is not expensive enough that you will accept it in return for lower prices.