And I had a blast!
I played on the Insane, and going through the first dungeon for the first ever time brought emotions I would never forget.
The hordes of undead, which reminded me of IWD.
Enemy AI, which focused on my mages instead of front-liners.
Enemies using Poison Weapon and hiding in shadows, to backstab my most unprotected characters.
Overall, I thought that the Insane now offered a good challenge (and this comes from the player who can't play BG without the SCS mod).
There're items with new abilities, from the perspective previously unused (who would have thought of an item increasing the level of turning undead).
There're puzzles in the dungeon. For example, for this particular dungeon it required from me about 30 minutes of trying to undestand how to solve that puzzle. Loved every bit of it!
Imoen told what she knew about each new room we entered. It was very refreshing to have a non-party NPC to tell about the in-game areas.
And, above everything, new lines and dialogues. They're very, very well written, completely on the level of BG1 and BG2. Nothing can be better than hearing the new lines by Minsc or Dynaheir.