While Baldur's Gate Enhanced Edition adds some interesting new changes to the formula, a slew of bugs hinder it.
To all who don't know Baldur's Gate uses the 2nd edition Dungeons and Dragons rule set and that will most likely be very overwhelming to newcomers who have never played a D&D game before. But nevertheless, the game's combat is very tactical and deep, controlling a party of six and pausing the game to asses and issue command and then see the action play out is immensely satisfying and the combat difficulty never strays into an area where it would be called unrealistically hard or easy.
The new additions, while good, are not really worth the 20$, especially since there are hundreds of mods that improve upon the original Baldur's Gate in almost every way. While the new arena mode called the Black Pits is very addicting, and the new dungeons added to the game are lengthy and fun, the new characters aren't that great from a combat perspective. Neera's Wild magic makes using her a gamble. Rasaad's Monk specialization is poorly developed and using him almost always ends up making him a liability to the party. Only Dorn manages to become an effective member of the party because of his enchanted sword and Blackguard powers. From a story perspective, all the new characters are quite unique each with his own compelling story and the voice acting is really great as well.
One of the most important things in Baldur's Gate Enhanced Edition is the absolutely amazing soundtrack, mixing bombastic symphonies in battle, to harmonious melodies while out of combat. The soundtrack of this game remains better than ever and the new tracks add to it.
I think that the main problem with this game is that many of the bugs from the original games carry here as well, from path finding to scripting the game has a slew of unfixed bugs that hinder this game's capability. But the many patches that the game is frequently getting help.
Overall the game remains one of the best role-playing games out there, for newcomers and fans alike I recommend a foray into this wondrous world. And while 20$ may seem like too much, the countless hours of fantastic combat and a compelling story will throw most doubts out of the window.