Six of One. Half a Dozen of the other.
Starting with the gameplay, this can be broken into combat and dialog mechanics.
Combat: Is both better and worse. Count me firmly in the camp that liked the changes to combat animations and effects. These changes added pop to the combat. I favor the mage for its cool explosions but was pleasantly surprised by how fun the rogue is, zipping about the battlefield leaping and striking.
The problem is there's too much of it. Just when you think you're done, you have another wave of baddies to fight. Always. And this can make the fighting tedious after a while. It is especially harmed by the context. Most of the combat takes place in and around Kirkwall where there are apparently a truly ridiculous number of bandits and apostate mages. Fighting large numbers of baddies made a lot more sense in Dragon Age Origins where there's a war going on and you truly are likely to encounter waves of Darkspawn.
Dialog mechanics. A lot of people have had a lot to say about the dialog wheel. I think the biggest misstep is having a designated "Witty" option. This undermines the surprise that is often essential to humor. Imagine a comedian prefacing his remarks with "prepare to be told a joke." And while that spot was also occupied by "neutral" remarks sometimes, having a designated witty spot puts pressure on the writers to produce a quantity of humor at the expense of comedy. The rest of the dialog wheel concept has similar issues.
I can see why they changed it. Separating the karma meter from the approval meter is more true to life. We all have people we care deeply about who we disagree strongly with. Plus it allows us to be liked without having to compromise how we play our characters. It just needs more work. They're about halfway to a great idea here.
The story is tighter with less player autonomy but more complex themes. There are missteps, the biggest one being the mages vs templars. Bioware understood that players would sympathize with mages since mages are cool and players like freedom so they went a long way to make the templars sympathetic. But they went too far. Mages and their attendant demons cause so many problems in this game that even Meredith comes close to being sympathetic. What is she supposed to do when mages routinely wreak havoc? When even Orsino resorts to Necromancy and when a leader in the mage resistance blows up the Chantry?