Intense fun, if you know how to stick solid to your role-playing skills! (small spoiler incl.)
Don't believe me? Try this:
Play through this as a Neutral Evil or Lawful Evil character. Work for that Throne! REALLY want to be the next Lord of Murder!! Stick to your role. Whether you are a being of your word, or have a dagger ready in each hand searching for someone's back in which to plunge them, you will thoroughly enjoy this!!
One of the funniest parts of this add-on is the NPC reaction to being dragged-down into the hells with you. The good and neutral NPCs display a fairly predictable reaction, except Minsc. The evil NPCs' reactions may make you wet yourself, so be sure to take a potty-break before the fight with Jonny-boy.
This add-on is best when played with a character that you took through the Shadows of Amn. I recommend that you take Seravok with you as a fighter, regardless of your alignment.