I have an iPad 3 and I wonder if there is a real life difference in use between it and the iPad air. I want to upgrade to Air but after I hear complaints about screen issues I decided not to.
Not sure what you mean about screen issues with the Air. It's an issue that doesn't effect many users at all. As for the 3 versus the Air? The Air is quite an upgrade in just about every regard.
It's a closer contest with the Air and the 4. We have one of each in the house and the Air is slightly quicker overall but it's not as much as you'd think. I still am glad I went with the air though, the lightness difference is rather noticeable.