Somebody over at m3post posted a really nice comparison between the F80 M3 and the E90 M3.
I personally have an E92 M3 and I do not plan on upgrading to an F82 M4 but it does look quite impressive and sounds a lot better than anticipated.
Cheers.
http://f80.bimmerpost.com/forums/sho...d.php?t=976284