The Architect brings the uncomfortable detail that darkspawn are only Always Chaotic Evil because the taint doesn’t exactly give them a choice. Once awakened, they can be as morally varied as any other race (if with a somewhat higher predisposition towards insanity; being tainted and then awakened seems to be pretty hard on their mental stability). Following his argument, a good portion of the hordes slaughtered during every Blight could be perfectly decent people like the Messenger if they were just capable of choice, making them as much victims of the taint as anybody else. This is somewhat countered by the reminder of howthedarkspawnreproduce. Then again, we do not know how long do the Darkspawn live and whether the Architect would wish to create more. There's also the fact that despite the Messenger's attempts to help people post-story, he does spread the Blight sickness.
The Mother implies that the Architect may not wish to free his brethren out of empathy for their situation, but simply because he does not wish to be alone,as the only sentient Darkspawn.
Angst? What Angst?: Sigrun is amazingly cheerful for someone from a caste called Legion of the Dead, and is promised to only pursue death for the rest of her life.
Oghren. Many people who disliked him in Origins warmed up to Oghren after Awakening, because he showed much more responsibility both for himself and others, and because of his new-found family. On the other hand, a lot of people who liked him in Origins found his portrayal in Awakening to be disappointing, feeling like he had significantly less depth and served little more purpose than occasional comic relief (the "shleets" conversation, for example). There's also a large segment who are just mad that the game retcons Oghren's potential death in Origins.
Velanna is an even bigger one. A large number of fans despise her for Jerk Ass tendencies, murdering a bunch of people with an incredibly flimsy motive, selfish reasons for wanting to become a Grey Warden, and overall shrill personality. Of course, a number of fans also love her for being one of the most developed characters in Awakening, along with her Hidden Depths and willingness to change her worldview if given sufficient reason.
Broken Base: Awakening either ruined Dragon Age forever, was a decent game that didn't have enough content for its $40 price tag, or was a great addition/conclusion to the story of Dragon Age: Origins.
One bug in Awakening will allow you to max out your level before you even leave Vigil's Keep for the first time.
Another good bug in Awakening: In the City of Amaranthine, the smuggler leader quest line can provide infinite gold. Perform the first two tasks, but refuse the third. Every time you go back, he'll repeat the conversation, Including the part where he gives you 15 gold.
A bad bug as detailed on the main page: If you import to Dragon Age II, whether you save Vigil's Keep or not, anyone not with you to fight the final boss will be flagged as dead.
And then there's the bug where next to no DLC equipment will carry into this game - cue players having an Oh Crap! reaction when the Warden charges into battle in naught but their underwear.
It has since been fixed (unless you're playing the Ultimate Edition), but until very recently, a bug existed on the "Legion of The Dead Heraldry," a mostly cosmetic, practically free bit of modification you can buy to put a different image on your shield. Instead of the normal +3 to all attributes given by other heraldic designs (which is a pretty hefty bonus for a cosmetic reward, all things considered), the bug caused the Legion of the Dead emblem to provide +20 to all attributes, easily making any shield to which it's applied by a far and wide margin the most obscenely powerful piece of gear in the game.
Hilarious in Hindsight: Asking Anders if mages and the Chantry are all he talks about; this ended up being a criticism of his DAII attitude.
Similarly, one of the banters between him and Oghren has Oghren making fun of Anders' "delicate" nature, and finishing with "Oh no, big templar man. What are you going to do with that sword?" Given Anders' status as Ambiguously Bi in the sequel (and in fact confirmed bisexual by Word of God), his "Ew" reaction is even funnier. It also makes a lot of his dialogue look like posturing.
It's Short, so It Sucks: Many fans weren't happy at Awakening being priced just as high as the main game, when it can be beaten in twelve hours or so.
Late Character Syndrome: Whichever character you recruit last (Sigrun, Velanna, Justice) will possibly run into this, despite that they are forced into the party during a certain point and are fortunately leveled.
Rescued from the Scrappy Heap: Not a character, but a place; the Deep Roads are only rivaled by the fade in terms of how hated and loathed they are in Origins. Awakening, however, tweaks this by making them far more visually interesting (exploring the ruined city of Kal'Hirol) and using them to expand on Dwarven lore in an interesting and compelling way.
The Woobie: Sigrun. She was a Casteless in Orzammar and forced to betray the trust of one of the few Merchant Caste dwarves who felt sympathy for the casteless and got them exiled and then joined the Legion of the Dead to make up for it. If you meet the dwarf Sigrun betrayed, she has some pretty harsh words for Sigrun.
Nathaniel Howe, he's completely looked down upon by all of Fereldan for the actions of his father Rendon and his entire family is worth less then dirt, which effects him pretty badly to the point that he has no idea what to do with himself until the Warden-Commander recruits him. Thankfully the Warden-Commander can help him and reassure him that he's not responsible for his father's actions (And if the Warden-Commander's a Human Noble, end the Cycle of Revenge between the Couslands and Howes). Or make things even worse.