I am also surprised why so many people are disappointed with the M3 because IT IS a much better car than before, the biggest problem the M3 has is that the competition has caught up and in one case far exceeded it.
I don't think the current RS4 is a better driver's car but it is a much better overall car if you don't value tail out entertainment as the number one priority. The same is true for the C63, it too is a better daily drive but falls apart when pushed to the same extremes as you can do with the M3. The only car which easily out classes the M3 is the mighty GTR but then it was never built to take on the M3, it had it's sights set on much bigger fish to fry but Nissan priced it so competitively that potential M3 customer also ended up as it's competition as well.
The problem is that some people's expectations were too high.