Well, what to say about this one? On many RPG-game community-sites, Baldur's Gate still ranks in Top 10 (just like the first part, Planescape: Torment and some other RPG games of Black Isles) although it is quite old and there is a reason for it.
Baldur's Gate II is a party based isometric strategical aD&D RPG game with a deep storyline, moral choices, real interaction between your NSCs, lore to almost no end... Almost anything a real good RPG needs.
ICompared to the first part of the series, there are some differences. The story is more linear. You have less open-world exploration but are driven either to your next main quest or to one of many subquests. This reduces the risk of newcomers getting lost in endless exploration without knowing what they have to do next, but I realy liked the true open-worldness of the first part, so this is a little downside in my opinion.
Everything else is still the same old-school RPG-style like the first part. So it is realy some kind of must-have for hardcore RPG gamers. Oh, and you can import your character from the first part which is a big pro for this game. There are only very few series which allow really carrying over your char.
This edition is shipped with the "Throne of Bhaal"-AddOn which was not the best Add-On Black Isles ever made. The story and the enemys truely seem overloaded and a lot exxagerated most of the time and so are the items and the "epic" skills your characters will achieve to beat the game (which is not very hard, even on increased difficulty levels). Buit still it concludes the "Bhaalspawn"-storyline of the series.
The Enhanced Edition comes with another campaign "The Black Pits II" continuing the arena-fighting campaign from the enhanced edition of the first part with even more arena fighting, but also with a deeper story and more tactical options and more roleplaying between the fights.
It also has enhanced graphics compared to the original game and some new NSCs with their own subquests and interactions. Some of them you might know from the Enhanced Edition of the first part.
The enhanced edition also has some new character classes, skills and spells, but those are only bonusses. If you already own the original game, have some great mods installed and don't like arena-fighting, this enhanced edition might not be worth buying, but for all the others it is clearly a recommendation.