PS:T is a definate change from BG2 or IWD actually. Much of it is scripting and talking, but damn, the dialouge and writing is GOOD! Personally I also felt the whole Bhaalspawn saga thing rather contrived.. like a cheap excuse for your character to get involved in stuff, but you never really felt like he was anything REALLY special. The thing about PS:T is that its as much a mystery as everything else. In this game, your past is REALLY in doubt, and it never lets you go. Completing a portion of the game lends the same satisfaction as reading a good, fulfilling book. Most of the game is spent at lower levels, and your stats are not predetermined: every level you get gives you an additional character point to spend on Str, Con etc so you can decide what sort of character you want. Classes can be switched at any time from Fighter, to Thief, to Mage. And NPC dialouge is actually important in this game. You'll be compelled to bring along the less potent characters just because they're horribly important to the story. Definately a breath of fresh air, but whether its to your liking or not remains to be seen. Go try it!
