4 out of 5 rating for Storm King's Thunder
WotC tried to make a true sandbox. They were and, at the same time, were not successful.
First of all, the adventure truly starts at 5th. The provided adventure to bring beginning characters from 1st to 5th is a joke.
Then, they provided 3 different starting points for the campaign. Nothing exceptional. After that, the PCs can explore the Sword Coast. WotC built a true sandbox, in the sense that the party can truly pass through every town of the Sword Coast and find something interesting to do. That is impressive: the Sword Coast as an open-world that can be used by the DM in many other campaigns. But this part is so free-form that it is easy to get lost. Meaning that the players, fascinated by the sub-quests and red herrings, don't know clearly what to do. IF all goes as well, the PCs discover the plot of the giants and can storm ONE out of FIVE of their lairs. Each of these dungeons is very good or masterwork, and the DM can use the excellent material provided later in this campaign or in other ones. Then, the final part of the campaign: the Storm Giant lair appears excellent but the NPC relationships make it a bit confusing (IMO), and the end appears a bit anticlimatic. A Giant campaign with a BBEG that is not one of them?...
Other ideas were underdeveloped, as the runes or the potions of growth (why? "You have to be a giant to defeat a giant!" But Please!). The art, instead, is excellent.
In the end, it is a good product with some excellent aspects that the DM can peruse, but ultimately lacks focus. As a consequence, the players lack a strong motivation. So I cannot give this product a 5-star rating.
WotC experimented with the idea of a true sandbox, surpassed the results of the first published adventures for 5e, and learned some lessons from the mistakes, and in fact some time later Tomb of Annihilation was produced: a truly well made sandbox.