I will personally wait until tomorrow afternoon and find out, side-by-side with my iPad 1.
Unless there is some programming wizardry involved in the apps that allow for smart scaling, it can't look the same. We all know what a native iPhone app looks like in 2x mode on an iPad 1/2. Any time you make an image larger, it gets blocky. If you merely turn each pixel from a legacy iPad app into 4 pixels on this display, it will look bad.
If the hardware instead does some sort of real-time interpolation (like DVD upconverting in a blu-ray player), then it would look fine. But that takes some horsepower.