My (very long) 2 cents on the PC version:
Bioware are known for writing good story, which is what keeps me playing their games, no matter how much they sometimes aggravate the cr*p out of me. I've played pretty much every Bioware RPG and I pretty much know how they work. So, to quote Yahtzee Croshaw, Bioware no longer get points from me for writing a good story - though going off the demo alone, writing was typical prologue cliche.
First impressions: the female walking animation makes me feel seasick (seriously, even I don't sway that much after several vodkas and in 5 inch heels) and the female voice actor sound so prissy I am hoping for a mute as soon as possible (why, when her siblings and mother sound perfectly fine?). Dialogue seemed a little disjointed, often with an odd pause before my character spoke.
Combat is quicker but a bit make-believe - I feel like it's pretty but highly unrealistic (yes, I'm aware it's a game, but all that spinning about on the spot so you can fire energy bolts from both sides, backhanded and over your head when there's nothing near you is just pointless animation). Also, we seem to be heading down that route of 'combat is too easy and we can't think of any interesting or mid-level enemies, so we're going to spam you with enough grunts to sink a battleship' which had me bored by defeating the same 15-skeleton combo over and over again in DAO. Combat in DAO was ridiculously easy as is, this looks easier. Nothing seems heavy or requires effort - this also applies during Flemeth's arrival, when she 'drags' a Hurlock corpse along the ground for a few metres without it actually seeming to affect her motion in any way.
I miss the tactical camera - as others have said, it makes aiming dificult, and you can't see what the heck is going on with your other characters. How can I pick tactics for a tough battle when I can only see 10% of it? However, that's something Bioware have been slowly edging towards recently and I've played several games without it, though battles in KOTOR etc were much smaller scale and didn't have enemies far away enough to need it.
Getting a bit further through (I only played the first section - not Kirkwall - I want to save the later plot until it actually fits in) the thing I found most uncomfortable was the 'cinematic' stuff. Quite honestly - the graphics aren't good enough to really support it. Everything seems slightly out of sync, and the faces just aren't real or expressive enough to really feel like you're watching people, in the same way that watching entirely-CG movies always seems that little bit surreal. Further to that, everything seems every so slightly blurry, a bit like it's been shot with a soft-focus lens, which might be due to the whole 'it's a story being told by Varric' but just gives me a bit of a headache. I don't know why it didn't jar so badly in ME - maybe because in DA, they seems to be focusing much more on faces, whereas ME was usually a slightly more distant viewpoint. Or maybe it's the new art direction, which has a pared-down but less-real feeling to it.
Lastly, the dialogue wheel. I was willing to be convinced. The main drawback with it in ME was that quite often, I clicked on an option that SOUNDED like what I wanted to say, and what came out of my character's mouth was nothing like what I had thought. If anything, this problem was worse in the demo, even with the icons, which didn't actually seem relevant. Also, I loved all the dialogue options in DAO - I actually used to re-load just to see what would happen if I took a different line, especially the jokey ones (yes, I'm that sad) but this just left me a bit... meh. As I said earlier, the female voice grates on my nerves like nails on a blackboard, which doesn't help.
I have one other issue with the cinematic voice-actor thing, which is that for me it spoils a lot of the replayability. Same with the 'inbuilt' character creation. I've completed DAO 4 times. I've completed ME once... and a half. A large part of this is because when I hear Shep's voice now, I associate it with my 'main' character, and it makes it harder for me to play someone who might be totally opposite. The whole voice-personality link I've heard about in DA2 (where the voice acting changes if you mostly pick peaceful options etc) might help a little with this, but I tend to be a ParaGade - not a shining pushover nor a cut-throat b*tch but somewhere in between, and I suspect this is going to screw up the voice acting and leave me sounding a bit like a bad cartoon of multiple personality.
I dislike the 'battle over, have some XP' system as opposed to the 'kill something, get XP' system. It makes each enemy feel just that tiniest little bit more pointless, if you're a level-up junkie like myself

I can't actually tell whether the final amount of XP for the battle is mathematical based on enemies, without playing it some more, but I still miss those little xp numbers every time you fell a bad guy
Errrr... that sounded like a lot of ranting. It is. I'm one of the people who played DAO because it used many of the things I loved from more tradiational RPGs - interesting NPCs, good dialogue, customisation, and of course because it's Bioware - good story. We know some of the customisation has been lost (if NPCs can't change most of their armour, then the stuff they come with had better be a lot better than the usual defaults - I mean, Sten's sword after all that faff was hardly worth it), the dialogue... well, I'll hold fire on that one till I play the full game, since this was just the demo. The NPCs likewise.
Overall, my thought from playing the first section is 'I'm playing a console game', one of those where it's a combat game with RPG-style levelling and weapons and some conversation - it definitely feels more like final fantasy style than the more traditional style of DAO. I'm going to play it, because Bioware have never let me down on a story yet, and in the end that's what keeps me and a lot of other people playing a lot more than pretty combat scenes. However, I do feel like a lot of the things I loved about DAO have been taken away, for whatever reason. The 'feel' of the demo to me isn't Dragon Age - more like what Jade Empire could have eventually evolved into (same flashy but unrealistic combat moves, same lack of weight to anything, same slightly simplistic mechanics). However, complex NPCs and a story with lots of possibilities will pull me in no matter how bad everything else might feel (to me!)
Last thing - did anyone else just find the slow-motion killing-blow animations in DAO annoying? I mean, the first few times, when you had a single ogre and that was it, they were brilliant. Later in the game when you had 3 of the b*ggers and a small horde of smaller spawns and everything went-all-slow-mo suddenly I found it really broke the immersion, not to mention being irritating as hell!