While the iPad has certain ecosystem advantages over the recently-released Surface with Windows RT, Microsoft's entry does of course edge out the Apple device in some key areas as well. And if you're actually trying to get work done, the ability to easily task switch on the Surface—using any input method, not just touch—is a huge advantage over the iPad.
I've said it before, and I'll say it again: Apple could seriously close the productivity gap between its iPad and the Surface (and other Windows devices) by adding one crucial missing feature to iOS: Simply allow users to task switch by using the ALT + TAB (or, on Apple keyboards, COMMAND + TAB) keyboard combination. Today, even those iPad users with keyboards need to actually reach up and touch the screen to switch back and forth between apps. That's just not tedious, it's counterproductive.
On Surface with Windows RT, as with all Windows devices, you have choice. And if you're a keyboard user, the previous app is just a simple and well-understood key combination (ALT + TAB) away. So even when you're using full-screen Metro-style apps, you can quickly move back and forth between two or more them, something that is not possible, or easy, on the iPad.