I'm suprised that so many of you are worried that the turn based fights of Original Sin are going to distract from the immersion. Have you played games like Fallout 1-2, Arcanum, etc? Or any roguelike like Angband or NetHack, games that don't even have graphics but still are among the most intense experiences you can have in gaming!
50% of your time with BG will be micromanamgent of your party.So I should have checked the manual to find out the default settings could be configured to drop the micromanagement all the way down to 50%? Gee, if I had know i could get it that low I would have bought it at full price rather than wait for a GOG D&D promo sale.

The combat in PS:T wasn't great, but it didn't require any micromanagement (only the occasional tough fight required characters being directed individually).
So true! If you play a good party in Baldur's Gate 2, it is very likely that the vampiers of Amn become your enemies. That means that you can't go out and buy a bottle of milk in Amn without being attacked by a bunch of vampires, and they make very short work of your heroes unless they have "Protection from Undead". Also, the vampires are immune to normal weapons. That means that your archers and slingers have to switch to +2 shots/arrows everytime they take a walk in Amn, and that you group your heroes together to cast the Protection spell on them all at once. The spell lasts for an inconveniently short time too, so you'll have to do this pretty often. If you don't have mapped a lot of Protection from Undead castings on your casters, you also have to go to sleep a lot to regain the spells you've used up. That's just how Baldur's Gate 2 is.
Many people are prepared to get used to the constant micro tediousness because of the memorable characters and story, but I was never able to do it myself. I almost finished Baldur 1 with my then girlfriend as she was a major fan and controlled 4 of the 6 characters over LAN, leaving me to do the dialogues and control the rangers. That was pretty fun. But really, the micromanagement is hell.
Planescape: Torment has an even better story, maybe the best ever told in a computer game, and while it demands the same type of party control, it differs in several important aspects. First of all, enemies hardly ever deal status effects like paralysation or posion and seldom requires advanced weapaons to hurt. It does happen that you get the "weapon ineffective" message from time to time, but generally you have the weapons you need and archers. As there is only one archer in the game you don't have to switch back and froth arrows depending on who you face either. Also, the battles are much less frequent and finally it doesn't even matter if you die. Your companions dying might be a little inconvenient but you can resurrect them much more easily than in Baldur.
By the way, does anybody here like Icewind Dale or Icewind Dale 2? I've heard that they are like Baldur, only with less story and more focus on combat and tactics? Is this any fun? Or maybe the lack of a story like that of Baldur makes the tactics bearable; could it be possible to enjoy the fighting when they aren't keeping you from unfolding a great tale?