When I think of an iPad, I think of something that's a natural progression from the iPod and iPhone, running bigger and better versions of the apps you can get from the Apple walled garden. It's a fantastic piece of hardware and a tight ecosystem.
Microsoft isn't just trying to compete by offering its own similar piece of hardware to run its own similar apps. They are looking to offer high-performance hardware (an Ivy Bridge chip in a tablet!) with great design, and they're looking to run full-fledged Windows applications.
They're not just competing with iPad, they're offering a possible desktop replacement tablet. That's a bold move.