The hook suffers from serious one-point failure. The PCs have absolutely no reason to trust this cloud giant who just showed up to a town that was recently ransacked by cloud giants, but if they don’t, the adventure just doesn’t happen. Also, there’s a huge chunk of the adventure that’s literally just “run some other adventures until the PCs are high enough level for the next part” with no other guidance. I’d be willing to bet the parts that seem “a bit lumpy” are the parts that are actually written in the adventure, and the good parts are entirely of your DM’s creation. Not because they’re going off-script but because there isn’t even a script to be on.