Yeah, I haven't even begun to scratch the surface of this expansion and it's already continuing the quality of the original game. They even added some general improvements as far as organizing your inventory is concerned.
You have to be a pretty high level before starting this expansion, like the mid 30s. Currently I'm already getting quests in the mid 40 range and I only just hit level 40 myself.
The setting is different. It's less of a grim tone and more fairy tale noble knight stuff though naturally there is a lot more shady things going on than the happy green place would indicate. Reminds me of High Garden from Game of Thrones. Still, the average citizens seem to be more civil and impressed with you and aren't calling you a mutant whenever you pass by.
Highly recommended if you already like Witcher 3.