The basic principles I would like to see addressed:
- If you have to railroad, hide the rails better. DAO and DA2 both had quite a bit of railroading, but DA2's rails were much more visible. Visible rails chafe quite a bit. Needing to fight both leaders at the end of DA2, and the nearly-identical endings were not hiding the rails well. Being unable to turn Anders in to Cullen was visibly chafing. In that latter situation, you could have just let the player hand Anders in, and then remove him from the group. Perhaps he could simply escape, and then enact his plan on his own. Major plot points should probably just have convergence of branches.
- Use less dramatic irony. Dramatic irony is a very useful tool for certain kinds of storytelling, but the problem is that when the player knows something that the character does not, it drives the player up the wall and makes them feel like they are losing their sense of agency - as it rightly should. This caused a lot of issues with situations like Act 3, the end of Legacy, the end of Mark of the Assassin, etc.
- Respect the player's choices. What we want is the feeling that our choices matter, even if they don't. The more blatant a "but thou must" situation is, the more it chafes. If you need something to end up at point B, make it a believable transition. I felt like the decisions with Feynriel mattered. I did not feel like the decisions with Grace and Thrask mattered. This isn't to say that you couldn't have had the same general outcome, but instead of finding Grace at the Gallows later just saying "We got caught anyway", you could have had an act 2 quest where the templars ask you to track down a dangerous group of apostates, who happen to be Grace and her cronies and then they get captured there. In act 3, you could have had Grace and her cronies be an apostate group working with the mage underground who are trying to work with Thrask.
- Companions need room to interact. I really enjoyed how the companions in DA2 interacted with each other. It gave them a sense of life beyond Hawke, and that was wonderful. There are a few things that grated on me over the course of the game (but were better addressed in Legacy and MotA). Specifically, I wanted to see more interactions with them. Put them all in a situation like the post-game celebration in DAO, where you can see Isabela fleecing nobles, Varric telling stories, Merrill watering plants, etc. For an excellent example of scenes like this, I would suggest playing through Persona 4. There are several character building moments over the course of the game (camping trip, school festival, cooking contest, etc.) where they advance the story and build character for everyone involved. And please, let them come and visit the protagonist at home, rather than coming to visit the protagonist's dog.
I really enjoyed a lot of the other systems in DA2. The friendship/rival system was wonderful. I enjoyed the cross class combos, and I liked thinking about the choices I had to make when it came to building a spec for myself with the talent trees. I really enjoyed the pace of the combat, once the spawning and waves were hidden better (e.g. Legacy, MotA), and I think that it's much better than DAO. I like the iconic looks each character gets, though I would like more customization options for them than simply two outfits. I definitely support more iconic-looking companions in the future, over more generic-looking armor selection.
For me, it's about character building. I want to feel like the characters I am interacting with are real, living, breathing, flawed people who change over the course of the game. If I can't believe that the characters can change, I have a hard time believing the world can change based on the actions of those characters.