you did a very good explanation of the game ,but you neglected to explane the additions or differences between this and Castle Ravenloft
(which would have been what I was interested in)
The primary differences are:
Different monsters (ie - every monster is different between the two sets)
Different conditions - ravenloft has slowed and immobilized, ashardalon has poisoned and dazed.
Different tiles.
Rules for locked doors and chambers - ashardalon has rules for doors being locked or trapped, and has rules for chambers, where instead of exploring and uncovering a single dungeon tile, you uncover an entire multi-tile room and are given a mission in that room.
Different characters - The rogue, warrior, cleric and mage are all in ashardalon, but they're different races and have different powers. All-new is the paladin.
Oh, and it also explains that at the start of the game you draw a treasure card
and discard anything that isn't an item - just keep drawing and discarding until you get an item, which was a bit confusing in ravenloft ("Yay, I regain 1 lost hitpoint! Before anyone has taken damage! Woot!)