It has no removable battery, only one USB port, and no Ethernet port. There is no DVD drive built in, so you need to either carry Apple's external superdrive, which kind of negates the whole purpose of an ultralight laptop, or use Apple's remote disc software, which "borrows" a DVD drive from nearby machines. Also, the Air's case is made of brushed aluminum, which transfers heat. I found the left side of the unit could get uncomfortably hot.
But there's no denying the thing is gorgeous. It feels great in your hands and somehow seems lighter than the VAIO, even though it actually isn't. The trackpad is large, and scrolling is intuitive. You use two fingers to scroll, one finger to mouse, just like the iPhone. Using the Air is like Christmas, your birthday, and Valentine's Day all rolled into one.
BOTTOM LINE: The MacBook Air really won me over. It does not compromise on keyboard or screen size. The Mac OS was fairly easy to use (though I'll never get used to not having a right mouse button). If you need to use Windows, you can install a program called Bootcamp, which switches between Mac and Windows. I now lust for this laptop and will switch to a Mac as soon as possible.