Ranked in these QuestionsQuestion Ranking
Pro Best-in-class trackpad
MBA has an excellent button-less muti-touch trackpad that's highly accurate and comfortable to use.
Pro Great keyboard
The MBA has a well-spaced, back-lit keyboard with convex keys and placed in way that the resting arms on the sides of the trackpad is comfortable.
Pro OSX is developer-friendly
OSX is based on XNU (Darwin) kernel, it's certified Unix and arguably a lot more developer friendly than Windows. Development for Unix is native on OS X.
There's a large selection of great development tools available for OSX. The operating system itself comes bundled with a powerful terminal emulator, called Terminal. Additionally, Apple provides tools, like Xcode, an IDE that contains a comprehensive collection of tools for developing OSX and iOS software, for free.
Pro Good battery life
The 11" model lasts up to 9 hours and the 13" model up to 12 hours. Great for programming on the go as you don't have to worry about the battery dying.
Pro Solid build quality and elegant design
Macbook Air has a high quality all-aluminum body that looks great and is sturdy enough that worries of accidentally damaging are mostly alleviated. It has a robust lid, well-spaced back-lit keyboard and an excellent button-less trackpad.
Con Low resolution screen
Depending on the model, the MBA has either a 1366 x 768 or 1440 x 900 screen and that's behind the expected 1080p screens of most modern ultrabooks.