I love it for the plot and writing that is far better than a lot of novels, and for the very unique world.
Do BG has any of those ? How is the gameplay compared to PS's (not so great...) gameplay ? And how is the world, is it just another generic D&D\LOTR setting or is it more interesting ?

BG is standard DnD fare meaning "save the world" plots are the order of the day, villains are rarely anything more than the paper thin "let's do evil stuff cos evil is fun" variety, side quests are for the most part the "Go there, fetch this, kill that" kind, your main character is all but forced to be the good guy, dialog choices are illusions (1 good option with several bad options isn't choice), well, you get idea.

If you enjoyed the game play in PS:T and haven't played BG, definitely give it a go regardless. Gameplay is similar to PS:T and BG is still a great game in it's own regard. It just isn't the pinnacle of RPGs like others cracked it up to be. However, if you are dead set on an RPG with good writing and involving plot, then I advise to give BG a pass as it has neither.

PS:T and BG are totally un-alike. I'm not even going to bother to say any more -- that's all you need to know -- since asking a stranger "will I like..." is an exercise in utter futility. Try it, and see.

There are many similarities and many differences between PsT and BG.

The world of BG is more classical (Forgotten Realms, a standard Tolkienesque fantasy world, even if it has its own features and history) than PsT. You get some taste of the weirdness of PsT in a few quests, but overall it's much more classical. The themes/plot of BG is the more heroic fantasy plot (even if it has its own twists and variation), not the highly philosophical and personal narratives of PsT.

But there also are lots of similarities between the two games, in the way for example that companions have their own personality and opinion on what you do, unlike most CRPG before them. They also both have a start with a similar feeling of being (nearly) alone, lost in a weird and large environment, and trying to find a way forward. Also in the way that the main character is someone special, which you learn more about as the game unfolds.

If you like it it won't be for the same reasons you love PS:T. Simple as that. If you want something that tries to reach close to the greatness of PS:T, I recommend Fallout 1+2 and Arcanum. Inquisitor is a great one too. All of those have great: stories, characters, writing in general, themes, atmospheres and overall experiences.

Give it a try, chances are quite high that you will like it.

They have the same engine, similar rule set, but the similarity ends here.
BG series do have good writing. Note, is good, not great.
In my opinion, BG1 is just another generic D&D, while BG2 is much more interesting.

I'll second that the writing is good (and only good, not very good, or great), but, the amount of it that there is for how much game there is is minimal. You might get 1 minute of reading dialogue of good writing for 3 hours of play. Now, I don't know how accurate that actually is, but that is what it feels like to me, it could even be less. A lot of the writing is stand-alone. Meaning, they wrote a little quest and when you finish it the story is done and it has nothing to do with the main story and never comes back. I would say that the main story is a very good story (once you get to it, very slowly in little bits until you are near the end of BG2 and into ToB when it really gets good and you get everything that you've been waiting for.) But it's probably one of the shortest stories that takes the longest to develop and finish in a video game. Do you want to play 150+ hours of game for a very good story with a lot of filler content (good filler, for the most part) ? There are many many many games out there with better writing. No game has better writing than PS:T.

Well, I've played PS:T and F1&2 and enjoyed them all. PS for it's world and story and Fallout for both world and gameplay (although not as Torment).

BG just seems to me ... Too generic. But many consider it to be at the same level of PS:T and Fallout, so that's why I'm curious about it.

Give Neverwinter Nights 2: Mask of Betrayer a try. Like PS:T, its strength is story and writing. Actually these two games are done by basically the same team.

Yeah, that always baffles me. To me, it's not even close. Try Arcanum.

I've played BG 1&2 PS:T all three are good games but if you're looking for BG to be like PS:T you will be disappointed. PS:T has a much more in depth story but BG1&2 are fun, too. I think you'll enjoy them.

I'd say, in general plot and writing of the BG series isn't as good and deep as in Planescape Torment; though BG 2 is somewhat similar to Planescape Torment concerning your party members who have backstories and quests of their own.
BG is much more combat-centric (with some occasional riddles thrown in, at least in BG 2) than Planescape Torment, thankfully the combat is much better than in Torment where it was fairly tedious.
First BG is pretty generic fantasy, BG 2 has more exotic elements (its setting, the nation of Amn is somewhat based on the medieval Iberian peninsula rather than Northern Europe, so it has "oriental" elements; also, some quests feature excursions to other planes, and one NPC, Haer'dalis, is actually even from Sigil, the city in Torment).
Hard to compare the two, they're pretty different, you'll just have to try BG to see if you like it...probably best start with the 2nd one though, the 1st can be fun, but is pretty dated now and rather unpolished (though it has its charms).

I'd add a suggestion of the NWN homebrew module "Tales of Arterra" to that list of suggestions. It's a more generic fantasy setting than PS:T, but despite that it feels quite similar to PS:T, in my opinion. Especially the later sections. There are 3 NPCs who can join you; I recommend looking up where they are before you start playing, as it's easy to miss them and end up playing through part of the first module without one of them.

I do recommend trying BG1 and 2, but probably not immediately after PS:T.

It isn't, remember your dialog options in PS:T? solomonhume and drealmer7 said writing is good but unfortunately it's only good at times and not very often. Some of the character interactions can be hit or miss to downright eye gouging awful. I've attached 3 screenies to show you how bad the writing can be. Also, yes, the screenies are from BG 2 but BG 1 and 2 are full of crap like this.

My advice is to not look at BG as an interactive world because it really isn't. If you look at BG like a slower paced ARPG, you'll have a lot of fun with it. BG is still a great game but in your original post, it seems you are looking for another believable world to explore and BG simply won't deliver on that front.

Have a look at the screenies and see the "top notch" writing. Is it to your liking? Because there's lots more where this comes from