I finished the game in 2 days, give or take, with a Mage. I rather liked my ending sequence though.
An entire Circle of Templars bowing before an apostate mage just seems rather awesome.
In my ending, Anders blew up the Chantry along with the Grand Cleric (!), I defeated the Qunari invasion by having a mass brawl in the throne room, Carver became a Grey Warden, I didn't manage to romance anyone, and I never actually managed to recruit Isabella.
I agree that in some parts the writing is bad. The gameplay seems rather dumbed down from the original DA, and feels more like a Devil May Cry clone then a DA sequel. Tactics seem less important when your party will be wiping out enemy waves in no time flat.
I liked the voice acting though, and I thought linking seemingly insignificant sidequests to the main quest line was a rather smooth touch. For example:
When I chose to answer a letter from Thrask, the Nice Templar, and spared the Blood Mages, I didn't realise it'd come back to bite me in the butt later on when I was working for Meredith.
Also, since I didn't have Isabella, I didn't know about the relic, leaving me with that massive brawl I mentioned above.