Ranked in these QuestionsQuestion Ranking
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 Light and portable
At 1.7cm thick and 3lbs, it's very portable and great for working anywhere.
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.
Pro Up to 12 hours of battery life
Great for programming on the go as you don't have to worry about the battery dying.
Pro Great 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.
For a laptop with relatively low specs, the price is quite high.
Con Not designed for upgrades and very hard to fix
To open the case requires a special Apple pentalobe screwdriver and a Torx T5 screwdriver is needed to remove parts. The RAM is soldered on the motherboard so it can't be replaced. Replacing the PCIe M.2 SSD requires buying a special adapter. The battery in the Broadwell Macbook Air (2015) is not glued to the case, so it is easier to replace than in other MacBooks, but it will probably be glued in future models.
Con Requires the use of proprietary firmware
The source code of the firmware isn't available for users to audit or modify.
Con TN LCD Panel means poorer color and a narrower viewing angle
Being a cheaper variant of MacBooks, it uses TN lcd panel instead of IPS. That means it has worse color accuracy and significantly narrower view angles. The panel only musters 60% of the colours in the sRGB gamut, and falls particularly short in the blue regions. As a result, the MacBook Air's struggles to reproduce a huge swathe of blue shades
Con Low resolution screen
The 1440 x 900 screen is behind the expected 1080p screens of most modern ultrabooks.