The plot is nothing to write home about in DA, but it's the characterisation that will draw you in. You slowly build up a team of fellow eccentrics, if you will, to save the world with - and they all have a reason to be there. You can talk to them at any time and they will offer thoughts and opinions.
Every character you meet in the game, however minor, has their own reasons for acting in the way they do and their own motives for why they do things. There are points where NPC reactions will depend on who is in your party. The world itself is so well thought out it seems to live and breathe - there's a real sense of history to it and you don't have to read codices or manuals to get it, because it's all there in play.
It's probably the most realistic world ever developed for a computer game (Rather than adapted from novels, tabletop RPGs, etc).
It's not a perfect game, don't get me wrong. There are some areas that are just too much fighting with no variation and others that get old fast in subsequent plays through. But it's still the best party based RPG of recent years.
(Best single character RPG being Witcher 2, of course. That is... incredible!)
