I haven't read all the posts so, I apologize if what I've written has already been mentioned. I've tried to be as generic as possible but, in some cases, I had to reference DA:O/DA2 content in order to try and convey what I mean.
Background: I own DA:O and DA:O Ultimate Edition. (Yes, I actually bought two versions of DA:O.) I also own DA2 with The Black Emporium DLC only.
My thought on DA2:
Art:
(a) The Japanese influence in DA2 was a bit jarring. I prefer the medieval setting of DA:O.
(

Generic icons for things like gear, clothing, trash, etc. and no flavor text made items uninteresting.
© Books should look like tomes. Letters should look like parchments.
(d) Armor should look medieval and there should be more variety.
(e) Darkspawn are not scary. I was expecting zombie-like flesh creatures in pieced-together armor.
(f) Female body types/parts are overly exaggerated.
(g) In DA:O and DA2, NPCs repeatedly say that elves are so beautiful to humans. But, in DA2, even the human
peasants look better than the elves.
(h) All content should be rendered using the game engine. No CGI tricks.
(i) More fluid interaction with hugging/kissing. No more puppetry.
Story:
(a) Invest the player into the story.
Example 1: The Escape from Lothering introduction. We don't see the darkspawn marching into Lothering. We
don't see Lothering burning in the distance. The scenario was like a cross between a story, a tutorial, and an
"epic battle Hawke". I felt like I was on the outside looking in.
Example 2: Hawke must work off the debt incurred for getting into Kirkwall. Instead of a time jump explaining
the one year of servitude, I would have preferred playing through that year and learning about Kirkwall's history and politics. It's also very disconcerting to see NPCs and Hawke chat like they're old friends/acquaintances and I have no clue who they are or how they relate to Hawke.
(

I don't understand why Hawke is given the option of owning the Bone Pit Mines. After the quest is done, the place looks deserted and there is no profit-sharing either.
© It seems that every mage in Kirkwall is resorting to blood magic. This is completely different from what was expressed previously (in DA:O) as I understood it.
(d) We never see what Knight-Commander Meredith does to mages in the Circle.
(e) In the Fade, I don't understand why we're required to click on a moving book and solve barrel puzzles in order to gain attributes. It would have made more sense to defeat all of the demons and gain the attributes as a reward for each demon killed. By the way, as shocking as this may seem, I actually like the Fade in DA:O.
(f) More sibling/parental background story and interaction is needed. I'd like to know more about Hawke's brother/sister/mother. I had no vested interest in the family.
(g) There were no Chanter's Board quests in the base game (like in DA:O).
(h) If I can't make choices that deviate from canon (like in DA:O), then the story fails to be personally endearing to me.
Companions:
(a) Companion interaction should not be tied to quests only. Give the illusion of free-form interaction. As the story progresses, I want to be able to speak with my companions and get to know them; even more so with romances.
(

More meaningful love scenes with better and smoother animations.
© If Isabela must be in the party in order to be given the option to do her side quests, then the same should be required of Merrill. Otherwise, bring back companion conversations and let players get the option to open up companion side quests via chat.
(d) I want to be able to equip my companions with weapons/armor.
Party Banter:
(a) Regardless of which companions are in the party, I want to hear them having conversations with each other. If there's a love interest, I want to hear my companions share silly/serious anecdotes with each other.
Environment:
(a) For a medieval setting, I'm thinking castles, farms, forests, etc. Instead, I see a generic port city with a coastline.
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Re-used/over-used maps.
© When a fight breaks out in the city, generic world NPCs should react until the fight is over (as in run away, cower in fear, etc.).
(d) Varric's interrogation should take place in an actual room rather than a black void.
Facial Features:
(a) I'd like the option to not look like canon Hawke or a variant thereof.
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During NPC conversations, some facial and eye expressions do not convey emotions well.
© The mirror of transformation should include eyebrow changes.
Voices:
(a) Racial accents should be standardized.
(

In some cases, voice artists need to convey more emotion.
© Standardize pronunciation of all game content (cities, races, language, etc.).
Combat:
(a) No more combat waves. Instead, one batch of enemies with more meaningful combat (as in NPCs have more hitpoints, better tactics, etc).
(

Potion and Healing spell cooldown timers are too long.
Loot:
(a) More mobs need to drop coins/equipment/trash/potions.
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Better loot from boss encounters.
Crafting:
(a) I don't see the need to gather crafting materials if all we're doing is ordering runes/potions/poisons. Either bring back crafting or do away with it altogether.