Hey there... Just thought I'd chime in.
I actually played in Ares group (I played the Archmage). I did not find the encounter as disappointing however. Two of our PC's were Uber, and to be honest, I wouldn't be surprised at them handling any situation that was thrown at them.
One of Adimarchus's forms was blinded for the entire fight. What really screwed Adimarchus was a spell (not sure the real name of it) where are rogue/druid hit him with blinding spittle. I'm really surprised they didn't give him something to remove status effects. (or did they and they just weren't used???)
We did completely botch the raise dead thing, but still, I'm was surprised that he had no way of countering somebody using status effects and especially using effects like Mirror Image, Project Image, Invisibility, etc..