Just a few quick points:
Raw performance is still important for upcoming games that may be too demanding for high levels of AA/AF.
Future DX9 performance IS important for those who upgrade infrequently (every 18 to 24+ months).
The price is too high if its performance will be quickly superceded (similar to the 5800 Ultra), or if it fails to perform as it should in soon-to-be-released next-gen games, or when other cards offer similar performance at a lower cost.
Most of the other points raised have been dealt with already in recent discussions.
Why would you buy a 5900U to play at 640 or 800 res with AA???