Most of Dragon Age's writing is in the range of strong to decent.
There are a some bad/annoying parts that really stand-out though. Mainly when the writers contradict established background and lore just to push a certain thematic agenda.
For instance, Gaider's quote regarding Howe doing things without Loghain's consent is used with the heavy implication that Loghain had nothing to do with the Cousland massacre. But there's way more evidence and perfect timing in-game to suggest that Loghain was involved with Howe though to what degree is unclear. It would have been better to keep things ambiguous here, but Gaider's quote appears to be ham-fisted into place in an attempt to keep the players from hating Loghain "too much". Which in turn kind of ruins Loghain's character because it makes him seem like an idiot and even more of a traitor for letting Howe get away with his crap while leaving things be could add to the idea of Loghain being well-intentioned, but ultimately in-over his head.
Gaider also further says that Templar powers require lyrium, but Alistair never finished his vows and could still use his powers. Plus, Cullen confirms that a templar doesn't get their first dosage of lyrium until after they take their vows which further backs Alistair's statement that lyrium isn't necessary. Keep in mind that Cullen's statement comes in Inquisition, years after Gaider's comment on Templar powers. Once again, WOG creates a contradiction within the game lore and supposedly makes out Alistair to be a liar who was snorting lyrium behind the Warden's back and possibly tricking the Warden into getting lyrium addicted.
Then there's the Dalish retcon. DAO and DA2 said that the dalish treasured their mages since they revered magic (though still had a reasonable amount of caution). Now suddenly we have Dalish clans who actually leave mages out to the wolves because there's a surplus population instead of giving them to another clan that may need them. I can understand one or two clans doing this out of necessity, but for this to be a general practice? Once again, a contradiction is created in an attempt to put the Dalish on level with the Chantry. Perhaps if this was a practice made out of necessity due to the mage-templar war, I guess it would be more understandable. But for this to be something the dalish do for hundreds of years despite their reverence for magic? Not buying it.
All of the above were likely done with the best of intentions, but had clumsy delivery that's muddled some background consistency.