The only things they really borrowed from ME was a modified dialogue wheel and a voiced main character. Aside from the odd poorly implemented paraphrase, neither of these really detracted from the game for me.
The main problems DA2 had were 1) limited time ad resources in the development stage resources which resulted the endlessly recycled environments. 2) A lack of agency as a result of the decision to tell a multi-chapter story without the aforementioned resources to tell a truly branching story. And 3) a combat system that while fun, eliminated any real strategic planning by having enemies come in wave and even drop out of thin air.
From what I've heard
so far, they appear to have a firm grip on what was wrong with DA2 and what does and (just as importantly) does not need fixing.