Just picked one up. They're really slow, if you get it with a SATA 4200rpm hd, its even worse.
HD/ram is non-upgradeable. looked online on how to do it, looks like a lot of work and could void warranty. 1.8" drive not the standard 2.5"
It gets hot.
Has that stupid button on the track pad. MBP has the track pad as the button it self.
Shitty speakers on it.
few usb ports, limited hd options, no super drive... remote drive is so uselessly slow too, so you have to spend 99 for the air super drive.