DA2 had quite a lot going for it, actually.
1. Interesting and generally engaging characters all-round. Not "mostly wankers", like DA:O - seriously, when Sten is one of the most likeable people in the party, you're in trouble. They weren't perfect, but definitely good stuff. Seriously I frequently wanted to punch Leliana, Zevran, Alistair, Morrigan and that rude drunk dwarf in DA:O, but DA2? I can't think of anyone except Anders and for reasons that anyone who finished the game is familiar with, not really his personality outside of that whole arc.
2. Better conversations than any other BioWare game, and BioWare are just light-years ahead of stuff in other games. The conversations flowed more naturally and "attitude" icons meant that I never got surprised by what I was saying - well, except in that the Hammer doesn't actually mean ragingly angry just "a good telling-off!", which did surprise me, but in a good way. Certainly it's a vast improvement on the dial of ME1/2, or DA:O's unread lines. I felt much more like I was "RP'ing" a character than in previous BioWare games.
3. Lovely VA on all.
4. Combat more fun than DA:O, and fun in general (DESPITE the teleporting-in enemies, 6 billion HP bosses, and so on).
5. Skill advancement well-handled and relatively interesting.
6. The banter. Oh jesus the banter.
7. The jumps forwards in time in the story, most of which avoided some severely boring stuff.
8. The story not being entirely central-character-dependent. From followers hooking up to people deciding to do stuff without asking you first, but that which made sense (rather than just being a plot-device), there was a lot of good stuff here.
I could make a decent-sized "bad" list too, but no larger than for DA:O. I think DA2 is definitely rather underrated.