It's hard to review this series as a whole, because the quality drops radically half way through. The first perhaps 12 episodes are great, with all the classic Miyazaki touches in the story and animation. I would give these first episodes a 9/10. And then it just gets really boring. The first 12 hours are really a complete story, and there's a lot of excitement and momentum, and then it felt like there was a second season (although as far as I know this was all part of one season) with a new, more episodic story, and it got really boring.
So watch the first episodes, because they are great.