I'm not so keen on them using a higher resolution screen for the mode7 bit. In MarioKart it doesn't look terrible, but in Pilotwings it looks a little odd and it looks downright anachronistic looking in the far distance in F-Zero, as you tend to do when playing the game and noticing the join between the mode7 city and the skyline.
So I wont be using it, but it's still an interesting experiment. I'd be more interested and likely to use it to be honest if they'd maintained the resolution but added anti-aliasing and higher resolution maths, as while that would break the pallete requirements of SNES hardware, it might look to me less jarring.
Edit: Clarified that that last bit of the first sentence was about F-Zero.