How can you say that it's both a massive disappointment and absolutely fantastic? If you think it's fantastic and are still massively disappointed, your expectations are set far too high.

I would disagree about the plot. There is a bit too much dungeon crawling, but I've only played the game 27 hours or so and I think there is ample political intrigue to keep the story going, though it does move slower than most of them, but that's to be expected when the story isn't of your typical save-the-world variety.

It's really just up to your opinion and how you like to play games. Personally, I don't think it's the best in the series, but the Gambits are a fantastic way to make random battles less annoying, the world is vast and beautiful, and full of things you can do, and the plot is far more adult than ever before. Top notch stuff.