Both points of view are valid, although I played and liked both games.
BG2 wasn't a graphics powerhouse even at the time of its creation, so if you care about graphics, Jade stomps all over it.
BG2's story is pretty simple, and there isn't a whole lot of depth to the conversations. Jade's story is extremely well written and hits some interesting philosophical points.
On the flip side, BG2 stomps all over Jade in terms of breadth. In Jade PC, you'll be fairly limited in where you can go, compared to the nigh-limitless areas of BG2. You also won't have the depth of inventory-management options that BG2 offered for minmaxing.
The combat is a wash. If you like Jade's combat, you like Jade's combat. It's about as easy as the combat in the first Prince of Persia game (Sands of Time), so don't go in expecting the difficulty of an arena combat game. Again, I enjoyed it, but I was about the right target audience -- a CRPG player who enjoyed the occasional arcade fighting game, but wasn't good enough to be bored by the fact that the Xbox version of Jade had easy combat.
(The PC version is supposed to be a fair amount more difficult.)
Like I said, I played and enjoyed both. If you go in looking for a hundred-hour game with a ton of side quests, you'll be disappointed in Jade PC. If you go in looking for a compelling story and 25-30 hours of fun gaming, you've got a very good chance of being a very happy camper (although some people of course still won't like it, either because they wanted more moral ambiguity or because they wanted something non-Asian in flavor or just because of the subjectivity of taste).