The term "thin and light" has a flexible meaning in the laptop world. Currently, to be truly thin, a PC must be in the same range as the MacBook Air. Still, plenty of thicker 13-inch laptops still exist that would have been considered thin a few years ago, but seem merely normal today. The Asus U31SD-A1 is just that sort of laptop. Its thickness is more akin to a 13-inch Apple MacBook Pro, but Asus' laptop lacks an optical drive. We reviewed a nearly identical Asus U31JG laptop a few months ago, noting that it was a solid computer but lacked an up-to-date Intel processor. The U31SD-A1 has a second-gen Core i3-2310M CPU and improved Nvidia GeForce 520M graphics, along with a markedly better battery life than the previous U31JG. It's an improvement in every way.
But all of this is packed into a chassis that feels uninspired and is topped off with a middle-of-the-road screen and speakers. If you can live with that--and a lack of higher-end features such as USB 3.0--then the U31SD-A1 might be right for you.
At $799, it's a solid performer, but considering that similar laptops like the Toshiba Portege R835 can be had for the same money, this doesn't seem like quite the bargain it's cracked up to be. However, for back-to-schoolers who need all-day battery life, the U31SD-A1 could be a sweetly sized and priced purchase.