Keep in mind that the screen illuminates the keyboard in the dark, so a backlit keyboard may be more for aesthetics than functionality. I never use it on my MBA.
Something I don't like about the MacBook Air (13"): Dedicated audio in/out -- there's a "hybrid" jack which annoys me. I thought lack of firewire would be limiting for older drives and external interfaces, but I don't miss it. I do run Windows when I need it for (minor) updates to files in solid modeling programs such as SolidWorks and animation such as Maya while traveling with a VM. Works great.