This would be a very nice update to a slightly outdated game. It gives a more visually pleasing UI and, in some places, a more functional one along with many other little updates and few larger ones. The problem is in the bugs that accompany the game. There are many that are simply game breaking that put you to a full stop right in the middle or just don't allow you progress. The second big issue (for me anyway) is the price point. This is WAY overpriced in my opinion when you can get the older version for half the price and are far less likely to have any sort of bug stop you from completing the game. BG2 is one of the best RPGs that has ever been made and it would be a shame if all the insanely awesome stuff in this jewel were missed out on by someone paying too much money for a game with bugs and only minor upgrades (upgrades that you could easily add yourself with mods in many cases). Bottom line, get the old version. It's just the better one.
