Going from DAO to DA2 is easy from a game-controls perspective. (Much easier than when going from DAO or DA2 to DAI!)
The "Framed Narrative" format for the entire story really threw me off, I really didn't understand until my third-or-so playthrough. And for some folk, the highly limited scope (single human option, with single through-line to the climax) and scale (single city and immediate environs, plus excessive map re-use) was extremely off-putting. As my high number of characters (>10) indicates, those things didn't bother me too much.
What does still bother me are the inability (without invoking the command console work-around) to skip the Prologue for each new game, the utter predictability of the "3 waves of kiting critters", and the incredibly limited NPC storylines. Merrill is always a stuck-up whinger playing the "nobody loves me" card. Isabela is always the baddest ass in the room. Sebastian is always a sanctimonious prig (although that is made a part of the story!)
Like others, I put most of the deficiencies down to EA having forced the studio to rush the game out the door. Writing characters with real depth takes a lot more time than writing cliché caricatures, which then leads to needing to animate all those additional scenes and record all the additional dialogue. In the end, BioWare had less than 18 months between the release of DAO and that of DA2 (Nov 2009 - Mar 2011.) If one reads some of the creative team's comments from that period, (n.b. Ion Zur's) one gets a sense of the pressures they were under.
I think it's obvious EA didn't make the same mistake with DAI, although maybe the pendulum swung too far in the other direction? 