BG2 Had it's romances, but it seemed that the female players got shafted with Anomen as their romance from the game. Thankfully there are mods to remedy this flaw.
It had a better more detailed villian in Irenicus and Bhodi.
Better scripting, AI and creature spawns.
Better detailed areas but limited in number compared to BG1.
Better minor quests. They were not simple fetch quests.