"Eh" would sum it up well. I'll try break it down to make it easier to read/review. This is for the PC version

Friendly Characters:
Anders - Awesome.
Sigrun - Awesome.
Nathaniel - Good
Justice - Got him too late to form a real opinion
Velanna - Got her before Justice but didn't give her much time.
Oghren - Didn't use him much.
But really, BioWare? Please stop using actors in Mass Effect and Dragon Age, it's really ruining immersion for me, or at least get them to do different voices. Even if they're great, I can't shake the fact that Varel = Zaeed Massani. And even though the VA is different, Alistair and Anders sound a little too similar, especially in combat.

Enemy Characters:
Utha - Eh, nothing was explained about her to those who haven't read "The Calling"; myself included. There should really have been a better explanation.
The Architect - Now, this one had me wondering, especially at the end. Was he good? Was he bad? Is he trying to trick me? I wasn't sure so I decided that the safest thing to do was, well, to kill him.
The Mother - Yawn. Yawn. Yawn. Creation goes wrong. Been there, done that, got the various novels/games. From her first appearance, it was quite clear that she was going to be a fight in the game, and I guessed (correctly) that she is a final fight option.

The Pre-Ending Story:
This is probably the weakest part of the game for me. Two factions of Darkspawn (effectively Father vs Daughter, in that the Mother = a creation of the Architect) are fighting each other and running riot in and under Amaranthine and just, basically, making a mess of things. So you're given a Keep to upgrade (Neverwinter Nights 2, maybe?) and troops to upgrade the gear of (Neverwinter Nights 2 again) whilst solving the issues of your people (Neverwinter Nights 2 again!). You find materials to upgrade their gear or your keep whilst solving these issues (I've got to say it again, Neverwinter Nights 2), and have to do a non-essential loyalty mission for your companions. Of course, there's different outcomes and “incomes” (as in things carried from Origins), so I can't say I've seen every single combination, but it just is a bit poorly done.
I'm supposed to be busy fighting Darkspawn and saving Ferelden yet again, so why am I the one running around finding resources? Why am I the one convincing traders to come? And why am I the one who has to go save some daughter of a poncy bloke? Well, I guess I have to thank the Darkspawn for their patience in these matters.
It's very similar structure to Origins, in my opinion. You start, get a few companions in the first place (Ostagar/Lothering is Vigil's Keep, where you get Oghren, Mhairi, Anders & Nathaniel, just as you got Alistair, Morrigan, Dog, Sten & Leliana from Ostagar/Lothering), you do three “companion” zones to gain them (Justice, Velanna and Sigrun) and you can visit Amaranthine whenever you want to do some side quests, just as you would visit Denerim to do the same.
It works, I guess, but felt a bit dry.

Gameplay:
Same as Origins, really. But I have to commend BioWare on giving you your healer very near the start (Anders), because that was a bit of a problem, for me, with Origins. If you wanted Wynne, then you had to do the Circle Tower first, admittedly my least favourite bit of the game.
Sadly, the gameplay is bugged. A lot. Approvals depend more on timing than on conversations! With Velanna and Justice, at least, I got +100 approval for basically nothing. Velanna gave it once I recruited her, and Justice once I'd given him an item. I also found myself unable to get 100 approval with some companions due to the sheer lack of gifts and points from dialogue. BioWare should either have increased the gain from gifts, made the +100 bonus either non-existent or unconditional, and added extra gifts to allow you to keep it at 100 if you have no gifts left.
Sadly, there's a Fade section but it's much better than the Circle one, although it gives stat bonuses and I couldn't really work out why. They really weren't necessary. It flowed pretty well though, and was over shortly, although I couldn't say I found it too enjoyable.
As for stats/gear/drops? Ugh. My character felt ridiculously powerful by the end (especially with massacre), I had too many talent points, and constitution is still relatively useless. I came very close to dying once. My character's profile is reading that I have 99 strength, including bonuses! The gear is still strongly aimed towards melee, and warriors in particular. I got some nice staves and some nice robes, but overall I think it's still best for warriors. The character I imported was about level 9, so she got boosted to 18. I finished on 30 and I hadn't done every side/companion quest. Levelling is too quick in Awakening!
And gems. Gems... Yeah, was I meant to save them or not? I was swimming in gold and my chest was filled with gems and low-level runes. I was really puzzled by Shale drops (i.e. crystals) from time to time, sub-tier 8 gear and novice/journeyman runes. If you don't take runecraftingything then you're really stuck for runes, not that I found them necessary with the power of weapons/armor. At least Origins was very forgiving in terms of crafting, and I wish Awakening carried this on.
The addition of Stamina potions is amazing, though, and I'm really thankful BioWare added them. They're useful especially if you're a 2H warrior without a set bonus.

Performance & Bugs:
Generally it performed alright, but Blackmarsh/Dragonbone Wastes upto the Mother gave me some issues. It started to really, really stutter and jerk around and sometimes go smooth, but then back to stuttering. I've no idea what brought it on, but it annoyed me quite a bit. There were times when the map lagged and some really long loading going on, which I thought 1.03 was supposed to address.

Some quests don't trigger at all, and it's a pain. There's also a lot of ambiguity in the quest text and it can get a bit frustrating. BioWare really should have tested this better, because it's a shame that I couldn't do some personal quests. Sigrun and Velanna's quests didn't trigger for me, and Oghren's quest was very vague and I couldn't continue with it, and I assume it's because of my approval. I'd given him all his gifts, yet wasn't really past ~60 so I couldn't continue.

Ending:
Boring. Most disappointing end ever. Kill the Mother (that was my ending, anyways), walk off, epilogue. The epilogue was alright but not overly interesting. Not to mention the completely non-obvious hint at a sequel/DLC/another expansion. To me, however, the ending didn't seem too correct for my character. She wouldn't “disappear” at all!

Conclusion:
Good but not amazing. Close but no cigar. Playable not overly replayable. There's not a great enough number of choices to really get more than a few runs out of it before every choice has been done. If the quest bugs were fixed, I think I would enjoy this a lot more and get a lot more out of it. I love seeing my little dwarf run around in Sentinel armor and stab stuff with her sword (The Mother's Chosen), but I honestly think BioWare could have done much better with this. Awakening, in my opinion, should have been put back until May at least and they should have put the time into bug fixing and tweaking the game.
I'll recommend the expansion easily, but I would suggest to wait for a patch to fix the near-game breaking bugs I experienced, and the game-breaking ones others have.