I have played about 12 hours so far on a system running XP with a GTS 250.
observations: the good

I haven't crashed once and the program has been incredibly responsive even though I haven't yet done my post-installation HD defragmentation.
So far, Bioware storytelling has met my high expectations. They haven't lost their magic.
My DA save game imported with no problems even though I had played with several dozen mods.
Overall, the quality of models, textures, and animations is very high and I've only played on the 'Medium' setting.
observations: the bad

While the textures themselves were well-drawn, the concept for the new Darkspawn art is markedly inferior to that from DA:O. They simply aren't daunting or fearsome to look at.
The speed of combat animations is ridiculously too high. Combat feels like playing high levels of an arcade game like space invaders. The 'tactical' feel of combat suffers greatly.
The game is too easy. I knew it would be, especially with all the DLC items, so I started my first game on 'hard' and it is still too easy.
Overall I think the designers made a mistake in oversimplifying the game. My biggest complaint is the STUNNINGLY poor decision to separate player and companion clothing and armor. It definitely qualifies as a "great WTF moment in gaming history". Is this a sop to console game design philosophy? Kitting a party is one of the fun things to do in a party-based RPG game. Why butcher it?
Silly oversized weapons are a flaw that DA 2 shares with DA:O. It was fixed with a user mod in DA:O.
Remediation for the bad

Most DA 2 flaws can be fixed by modders if a toolset patch is released.
An option to reduce combat animation speeds desperately needs to be made available.
Unfortunately, the bone-headed companion armor idea is likely to be difficult or impossible to fix by modders and it is highly unlikely that Bioware would undertake the code-level revisions necessary to revert back to the successful DA:O model.
Game Prognosis

DA 2 is a good game. I'm glad I bought it. I am not sure yet, however, if it will be a multiple playthrough game or if I will buy DLC content. I can easily see myself going back to DA:O or on to other games if the combat speed and companion armor design flaws are not fixed either by Bioware or by modders. It would be a shame if the obviously staggering amount of highly competent and creative work that went into DA 2 didn't manifest as an industry-standard hit like DA:O.
Omg it just occured to me that maybe the companion armor fiasco was implemented to sell DLC. If I see DLC next week selling a bunch of new companion armors that will be the end for me. I
wholeheartedly approve of the DLC system and have purchased all but two of those available for DA. However, DLC needs to be content that adds to the original game and not content that fills a hole in the original game placed there to sell DLC. I realize that the new system is more akin to the way things are done in the Mass Effect series. However, that was a CONSOLE action quasi-rpg game (a great one to be sure). PC RPG'ers expect more and speaking for myself if I don't get it I'll move back over to Bethesda games. So far their games don't spin wonderful tales like Bioware, but they are true RPG games with solid DLC and excellent player-mod supported replay value.