"The following is less about replayability, but more a prefence: To me BG2 also marked the beginning of Bioware moving away from recreating a TT adventure feel and going into a more "interactive movie" kind of direction, as not only did they introduce more traditional cutscenes (as far as the Infinity Engine could handle them), proabably in parts influenced by JRPGs back then, which provided very different experiences back then when compared to contemporary Western CRPGs. They also got rid of "downtimes" / "travel" or anything in between adventures/quests, plus you exclusively find new locations on the map solely via getting a quest. Locations that also are chock full of "points of interest", which mostly seem to serve the sole purpose of advancing the quest's story most of the time. No more houses, locations or huts in a forest / settlement forest existing because they may just do that, existing."
WOW, this is an excellent explanation how BG I differs from BG II. A lot of people felt this way, but few have been able put it into words so well. BG I had a relatively open world, where you did not have to follow the main road on that first map. Exploration simply for its own sake was mostly lost in BG II, in favor of a tighter story-line.
