In two words?
HELL YES!!!
Baldur's Gate II is IMHO the best RPG I have ever played. If you like RPG's and you don't buy this game you are really missing out on an amazing game. The graphics are better than BG1 because it supports a higher resolution (800x600), plus you can select "unsupported" resolutions up to 1600x1200, and you can even drop the interface and go full screen. It also has 3D spell effects which look great.
The best part is the gameplay though. Of course its similar to BG1, that game was awesome, and BGII is just the next evolution. They added 130 new spells so there is now over 300. They also added character kits. The game itself is HUGE, there are so many areas to explore, that you might not even see all of them. There plenty of quests just for the main story line, plus tons of side quests. It almost seems like every person you meet might spawn a side quest. And theya re not just the standard FedEx type quests, there is tons of variability in the things you have to do. Plus, the NPC characters that you add to your party talk with each other, form little love dramas, and they can spawn quests as well. You even get to take on quests that can get you a stronghold.