How anyone can say the combat in DA2 is better than DA:O I just don't know.
It's certainly *flashier* but it's significantly less complex and interesting. For the most part if you pick, say, a Rogue you don't need to do anything other than mash 1 ability and watch your character spin around blowing people up. There's also less variety in enemy packs; being attacked in the street by 10x wave of 5 melee bandits isn't exactly engaging. They serve only to slow you down since they're never actually a challenge.
With Origins (and moreso with Awakening) there's a lot of build variety and flavour to be had. For example you can build an Arcane Warrior as a Mage with almost no energy for abilities but a lot of sustains that buff your group and help the Mage resist damage. The Mage options in DA2 are mainly based around what element you want to use, rather than having a real play-style defining choice. You can build a 2-caster team who focus on spell combos such as Paralysis Explosion or Shatter, and you actually need to use such combos to survive. You can have a team with 3 Warriors all doing different jobs. A Rogue focused on taking extra damage with sustained damage or one that's a complete glass-cannon who deals massive damage in bursts. You don't get that same variety in playstyles in DA2.
Using terrain, doorways, abilities and class-combos is a lot more important in Origins than in DA2.
There's also a big problem with location variety in DA2. For the most part, 1 cave will serve as the staging area for like 5 different missions at different points in the game. It's a big drawback of the game compared to Origins where there was a lot of variety and few repeat visits to any 1 area.
I still enjoyed DA2 though, it's a good enough game by itself and the combat isn't all bad. Like I said it looks really nice and is slick, but it's not got the same depth as the previous game. The story was alright, a few "oh shit" moments and cool characters. I still sunk 58 hours into it so :P