Soul-Suckingly Delightful.
The first several hours are essentially a tutorial, and aside from the story, they are rather boring to those of who are used to more action based games. Once the tutorial finishes, though, you are pushed into a world that will suck your soul right out of you. This is literally one of the most immersive games I have ever played. There are times when I go to new towns and miss the ones that I was in before, and the level of excitement I feel when going to new places is more than I could ever ask to get out of real life.
The story is awesome, and it is mixed with the gameplay in relevant ways that make what you are doing make sense. The entire feel of the game (at least to the point that I am at right now) flows very, very nicely. The side quests are usually fun and rewarding, and they are typically the only places where you will see fetch quests or kill-10-of-these-and-return-to-me quests, which is nice.
Finally, the art style is phenomenal. It looks like a cartoon, but the attention to detail makes it feel like you are in another world, not playing a video game. There is an example of a time you are in one of the beginning cities and you walk across a glass floor. Your reflection and your shadow match perfectly, down to the waves of your cape. When you run up and down stairs, you actually step on each one. It is incredibly realistic for something so non-realistic. It really has the Ghibli feel to it.