Immediate classic! This takes me back.
You start off, with a bit of background, you end up getting inducted into an elite group called the grey warders, and then ZANG you're off, from there, I couldn't put the controller down. The background seems a bit irrelevant, but comes back to haunt you at various parts of the game.
Your purpose is to fight off a blight -- an army of undead like creatures are trying to take over, and the grey warders are a bit scarce, thereby your job is to go around the map, gathering up all the help you can get in preparation for the big showdown.
That's pretty much it in a nutshell.
Tons and I do mean TONS of side quests -- as you go about gathering your war army, it seems even the ones who are obligated to do so are in dire need of help and essentially you act as a gopher to tide things over. Each town you go to also have random NPC's in need of help or favors, and usually there's a quest board. Make sure you clear each town before the showdown, I figured I would get through the game then go back and finish the quests, but apparently most of the continent was on lock down at the end.
Definite replay value -- I'm already wanting to play through it again and just simply not be such an a**hole, maybe another race too.
Even your teammates will have their quests -- Through certain actions, the group you travel with may come to love or hate you, this can lead up to all sorts, I definitely want to go back and try the ladder. Also, that's my favorite part about this game is when you're running around randomly your team mates will start arguing with each other, it's hilarious.
WARNING -- Do not play this game if either you're a student, or have one of those jobs you can't do on auto pilot. This game will rob your focus even when you're not playing it.