I listened to the base setup and the Premium using my own CD and could clearly hear the difference and am going for it.
It gives you tweeters in the A pillar, in dash six stacker, 150watt amp and the sub (not a douf douf job), DSP and a nice idea that allows you to adjust the balance for driver only, passenger etc. You also get the colour screen which matches better with the gauge colours at night and most importantly it displays the Ford Oval at start :)
Can't comment on the leather but have tried it out and its certainly nice to sit on. To me though, the leather interior looks too plain in particular the door trim which reminds me of a taxi pack.