See like, the thing about that is with different preset backgrounds, different races, and even different origin stories, there's a lot of stuff you can do to further explore places you haven't already, and often times it can completely change the way the story feels, even though it all lines up on the same storyline. Not even including campaign mode where you can make your OWN story. It's pretty in-depth, though many of us and Larian Studios know it was lacking in many areas, but I won't share those with you since I'm sure you'd like to play through the game first and enjoy it how it is.
Don't let people tell you everything wrong with the the game until you've beaten it, since by the time the Enhanced Edition comes out, you'll have probably gotten a free copy of the EE and those problems I've aforementioned will have been removed.
There's a ton of depth in the base game, not even including the thousands of mods the community has made, including new classes and characters. Hell, there's 4 difficulties to the base game. It's just really fulfilling to dig your teeth into and eat until none of it's left.
TL;DR Das dat shit I do like