Whatever else can be said of the Asus Taichi 21, it's unique. This Ultrabook features a dual-screen: a standard internal display, and a touch screen display on the exterior which enables you to use the Taichi 21 as a tablet when the lid is closed.

The Taichi 21 runs Windows 8 powered by a Core i7 processor with an 11.6-inch screen (1920 x 1080), 4GB of RAM, Intel Graphics 4000, 128GB of SSD memory, and a 5-megapixel camera on the outter, tablet display. Pricing starts at $1,299.

The dual display enables several interesting features. There's a mirror mode, which lets you show the same image on both screens. A dual screen mode shows different apps on each screen. Finally, close the lid and you're in tablet mode, touching your way around the 11.6-inch display.

While the Taichi 21 broke the Ultrabook mold with its dual display approach, it didn't win over most reviewers. The biggest knock was the battery life, which was rated poor even when powering just one screen. The lack of an internal touch display was also frustrating, given Windows 8 touch-centered operation. Some reviewers appreciated the novelty of the Taichi 21 and most hoped to see more from a second generation product -- if one should ever materialize.