1st act main quest was completely changed. There is new metaquest which will guide you through whole act. You need to read NPC monologues carefully as well as follow quest log instructions to complete this metaquest.
Akara' reward (for Cain rescuing) was changed:
Normal - 2 rare rings, Civilian's Ancient Key, Standard Ruby;
Nightmare - 2 unique rings;
Hell - 2 set rings and 2 unique rings.
Output of Charsi' Imbue action was changed. Now it is unique item, or rare item in case your character level less than item level of unique item.
Andariel drop was changed, there are random Mystery Potions and Gem Powders now.
Important monologues:Varriw introduction.
Akara monologue before Den of Evil quest accepting.
Cain monologue after rescuing him.
Kasya monologue before Blood Raven quest accepting.
Charsi monologues before Horadric Malus quest accepting and after quest completion.
Alkor potion is not drinkable anymore. You need to transmute it in Horadric Cube with any magic jewel in order to get 2 random Mystery Potions.
Ormus will give you Blank Stone instead of ring after Gidbinn quest completion.
Hell Forge drop contains random runes and gems.
Hell Diablo drops Annihilus with 25% chance.
Important monologues:Tyrael monologue after Diablo death.
Larzuk make maximum possible number of sockets in item.
Qual-Kehk give 5 random runes for soldiers rescuing.
Resistance Scroll of Malah don't give resistances anymore. Instead it is important component in some Horadric Cube recipes.
Anya give random unique class-specific item for rescuing.