The way the narrative in the game was presented did, in fact, at times leave the player with the sense that they were making monumental choices and having to live through the consequences.
But then if you play it again you realize that very little of what you thought you were choosing was actually a choice - the thing with your siblings was, but the way it works is that whatever you choose your family is still going to be fragmented. If you take them to the Deep Roads without Anders in the party, they die, if you take them with Anders they can leave to become Grey Wardens and they're gone, if they stay home they join the Templars or get carted off to the Circle - whatever you do, they basically disappear for most of the game.
Likewise with the big conflicts - whatever you do, you end up fighting both sides anyways, making your choice to help or support either side during the earlier stages of the various quests all but meaningless. Dragon Age 2 is simply relying on the illusion of choice in all but the most basic of ways, and the game undermines the choices it does let you make. Purposely let mages escape after demonstrating the dangers of blood magic? Too bad! They've totally been captured and now hate your guts and bitterly turn to blood magic, making you kill them. Also they kill the guy you saved by being conciliatory earlier, so that binary choice between kill/imprison mages or kill templars that you sweet-talked your way out of? Now they're both dead anyways!
Far too many events play out exactly the same or take contrived U-turns for me to describe the story of that game as anything other than "rail-roaded" - the designers clearly have a specific plot in mind and they don't need you mucking things up by having this pesky "player agency" that might mean having to design an actual branching narrative. What was that game recently that let you completely change the fates of kings, kingdoms, and the outcome of a bloody war simply by choosing different actions along the way, to the point where there's an entirely different second act based on a choice you made in the first one? Oh right, The Witcher 2.
Dragon Age 2 has choices, I'd be a blind fool if I claimed otherwise, but only the ones regarding your companions and how they feel about you actually end up making a difference, and even then there is virtually no impact on the narrative whatsoever - whenever a main quest presents you with a choice, you can be damn sure that you aren't actually making one; whatever you choose, in the end the results will be exactly the same. Turn a particular blood mage "innocent" of the crimes you were investigating in? He gets executed. Don't turn him in? You end up killing him anyways - all paths lead to the same outcome, Bioware had their two final boss fights and you're damn well going to play them and be greatful for it! It's to their credit that they hide that from you well on at least the first time through the game, but the replay value tanks significantly the second time around once you realize that while you can do things differently, it isn't going to matter much.
Dragon Age: Origins also had the over-arching story that no matter what you choose would unfold pretty much the same way each time, but at least the various choices it asked you to make along the way generally changed stuff.
In summation: There is nothing wrong with a linear narrative, but there is definitely something sketchy about designing a game you trumpet as revolving around choices, only none of them actually matter because your overall narrative is a bloody straight line - whenever it looks like something might branch away from the intended path the writers redirect it back to the "one true pathway", oft times off-screen during transitions between "chapters". Coupled with the extremely lazy art asset and level re-use and the other issues people frequently raise when the subject of Dragon Age 2 is broached, and it's easy to see why so many people were bitterly disappointed by it. It's not a "bad game", but it is a mediocre one and probably the worst game Bioware has ever released. People complain so bitterly because they really want Bioware to get the message that they can't phone stuff in and expect us to be happy about it, not because the game is awful garbage that no one should ever play - the problem with Dragon Age 2 is that it should have been so much better, and it definitely could have been, the potential was there.