It's meant to stand alone if you want, it's directly continuing the BG story technically though..
Like the first dungeon is filled with characters from BG1 but they kind of do the whole.. remember its me, I'm the so and so and kind of explain everything anyway.
I guess I should warn though some people have said the game itself was very punishing relative to the norm... the bigger issue isn't story-line but D&D mechanics, such as having mages memorize spells and only retain them after rest and a dozen other things like that, as well as managing 6 party members at once. There's no like trinity type system (tank, healer, dps), and for instance, characters can permanently die, and your starting stats are extremely important despite nothing really indicating this.
However, you can still rely on things like quicksave, pause, and auto-attacking in ways that mean with some patience and diligence I feel like it ends up playing more like games of today. You can also just kind of ignore some of the really crazy stuff like the Demi-Lich fight. If you quicksave a lot but lose a character to perma-death you can just re-load and try again. Plus you start out with simpler stuff it's only later in like the Illithid lair that things can get really hairy.... Infinity engine games are definitely a different style. For some people though that's all kind of part of the appeal though.
NWN is kind of a slightly more accessible version but it's still pretty heavily D&D, and building your class/perk stuff among the many options can be daunting.
The closest thing to this all is probably pre-first patch DA:O. Personally I found the Inquisitor sub-class of Paladin to make the game the easiest overall...