What is the Aero desktop experience?

glass visual effect

It includes distinctive visual styles that combine the appearance of lightweight, translucent windows with powerful graphic advances. You can enjoy visually appealing effects and appearance and also benefit from better access to your programs.

One of the more visually obvious features is glass window borders, which let you focus on the contents of your open windows. Window behavior has also been redesigned, with subtle animations accompanying the minimizing, maximizing, and repositioning of windows to appear more smooth and effortless

The Aero Desktop Experience is a combination of glass-like visual effects, widgets and color schemes that make the desktop unique compared to how other themes are implemented.
http://www.vikitech.com/5094/windows-7-aero

It will provide the windows operating system with more graphics and animation stuffs during the accessing different feature on it. More improved thing, but it will eat more battery.