From what I can tell, the iPad air uses the newer "mechanical" home button that got introduced with the iPhone 5. It's more durable and clicks/feels better IMO. The iPad mini 1 and retina iPad mini use the old squishy home button that was found in older iPhones. It is probably a little harder than the iPad 2 home button, but it is IMO in a good way. Should feel similar to your iPhone 5 home button though.