Recs.
Updated
SpecsUpdate
Pros
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.
Cons
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 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