I would hardly call the iPad Air a "sturdy" appliance. With all other issues that the iPad Air has aside the thing is nowhere near as sturdy as any of its predecessors. Check any of the drop and durability tests. Apple made some sacrifices when they went thinner. I can distort the LCD and front glass with my index finger and I can twist the chassis (tried not to break the display model).
The Air is a step in the right direction but it's only advantages over a 4th gen are being lighter and having a faster processor. But if you look at the trend in iPads the next version will be twice as fast as the current with a better camera, touch ID and most likely a better battery. Oh and let's not forget the whole RAM issue with it being 64 bit

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I believe the battery replacement program for the iPad cost $99. They don't remove you're old battery, they just recycle you're device and give you a refurbished unit. Plus you'll probably get the newer A5 which is awesome when it comes to battery life.