1. Repetitive dungeons, often the same cave 30 times over with barrels shuffled around.
2. Serious pacing issues caused by insanely short development time.
3. Enemies dropping in from the sky or appearing in puffs of smoke / "wave" combat.
4. Some story issues caused by insanely short development time.
5. Ambitious three act structure fell short of promise (due to insanely short development time).
6. Graduation from a more "old school" BG2 era style RPG to a more "modern" ME era style RPG, which rankled some.
7. Mediocre, formless main character.
90% of Dragon Age 2's issues can be attributed to it getting maybe 1/4th of the development time it needed. It was rushed from start to finish, and it showed.
Also, people love to pile on when they smell blood in the water.
Frankly, it's kind of amazing the game ended up charmingly mediocre instead of utterly broken ala Ultima IX.