I use seven (7) different tablets on a daily basis, I've become very familiar with the options. And yet there are times when I don't realize when I'm using and iPad 2 or iPad 3. The retina quality just isn't always apparent. The screen on the iPad mini is special though, similar to the iPhone5 and Macbook Retina where the image is much closer to the front of the glass. This makes a big difference.
There is a night and day difference between iPad and Windows 8 or Android. The Nexus 7 is the first Android that is usable and has a compelling reason to exist, namely the size and weight. With iPad mini, if you can afford a premium experience, it can satisfy the size and weight needs that you get currently with Nexus 7.
The iPad mini might be the first tablet I spend my own money on. And yes, it has 4G/LTE cell data + GPS, if you spend the extra coin for it.