Thoughts on Storm King's Thunder

Giants crushing Phandelin (or they should be)

259 page adventure that takes players from 1st to 11th level, or 5th to 11lth if you enter from Lost Mines of Phandelver and skip the first chapter. And there you have a good example of the first problem with this module, throw away content. The thing is 300 pages but:

1. 16 pages is skipped if you started with Lost Mines of Phandelver
2. Chapter 2 has you pick one of three attacks to involve the party so you use 6-9 pages out of 25.
3. 60 pages is a gazetteer of the Sword Coast and not really specific to this module.
4. The bulk of the Campaign has you pick one of five paths, each of which average 10 pages so we're throwing away another 40 pages here. 

So you are skipping half the book. Yes some might run it again and use the skipped parts but for most that's a huge waste of content. That might have seemed like a good idea to the wealthy folks at WotC but that's just crazy. Also I think as an adventure path its falls apart at some point. 

How I Would have Designed it Differently

1. I would have removed the gazetteer section entirely. That should have been added to another product, along with the maps and info for Nightstone, Bryn Shander, Goldenfields, and Triobar. DMs using the Forgotten Realms could use this sort of reference info and shouldn't have to buy an adventure module to get it.
2. I would have loosened up the structure a lot. Removed the adventure path and left it as a bunch of site based mini-adventures that aren't necessarily linked into one grand campaign. 
3. I would have dumped the Great Upheaval and started the thing at 5th level as one of two followups to Lost Mines of Phandelver (Phandelver and Below the Shattered Obelisk* being the other). I would move Dripping Caves to Phandelver and Below as well.
4. I would create a Southern Giants Mini-campaign. Fighting against Hill Giants with the Stone Giants there as a possible addition. Take the Goldenfields attack and rewrite it to be an attack on Phandelin. The PCs presumably have some investment in saving the place. Set it up so the players have to figure out how to defend the place or lead the Giants off or whatever. The players can then track the attackers back to the Den of the Hill Giants (which has a great map) to free captives, scout out the area for greater powers, or whatever they think might work. Lastly I'd yank Steading of the Hill Giant Chief (the old G1) from Tales from the Yawning Portal (released a year later) and put it here with better maps. The Canyon of the Stone Giants would be there as well, these two might be wound into the mini-campaign as another threat, or allies that could be used against the Hill Giants.
5. Next I would create a Northern Giants Adventures. This would include Berg of the Frost Giants and Forge of the Fire Giants (both of which have great maps) as well as G2 Glacial Rift of the Frost Giant Jarl and G3 Hall of the Fire Giant King (both with cleaned up maps and removed from Yawning Portal where they don't belong). This mini-campaign is just a bunch of stand-alone adventures easily justified by Giant raids. When Icewind Dale: Rime of the Frostmaiden was released 4 years later it would include notes on how to include the Northern Giants Adventures into the mix. Also whichever product had a better map of Bryn Shander would get it.
6. The Cloud and Storm Giants would be stand-alone adventures. Just sort of bonus content for a really high level challenge. 
7. I would take a note from Tales from the Yawning Portal and include a bit about where the different adventures might be located in Forgotten Realms or in Greyhawk or other settings.

It might not have been a perfect 259 pages my way but I'd be happy to dump the Cloud Giants or even the Storm Giants if we need space or add a second Stone Giant adventure if we need to bulk it up a bit. The point is that all the giant modules should be in one product and they don't need to be connected. I'd probably add Mountain Giants and ettins and other Giantkind to the adventure to show how they fit into the mix. There is also a 4E product Revenge of the Giants that could be looted and updated for 5E if it has anything worthwhile.