Usually by now I've collected links to many takes on Ambercon. Here are a few:
Claimh Solais: Ambercon 2004- In review
Amber on Amber: weekend review
The Non-Euclidian Staircase: My AmberCon US Report
point out more of these and I'll link them up
[update]
Kris F ACUS review
Chris K ACUS review
Ian @ Crouching Tiger