Ran this quests twice tonight and ran into some issues (beholder not spawning, drow death priests not spawning, INT rune needing over 60 INT on LE, etc), but that's not what this thread is about.
Tempest's Spine is my absolute favorite quest in the game, but I'm a quite disappointed of the Legendary version. I was completely expecting to see a new story, with different enemies, and certainly a different enemy end fight. Unfortunately, that's not what we are getting. It's just a simple cut and paste of the Heroic version, including the story, only with enemies who hit harder (like fire elementals who shoot Meteor Storm) and have more hit points. Frankly, I was bored.
Story-wise, it also makes absolutely no sense. We already killed Sor'jek at level 10, and then killed him in his lich form at level 17. Suddenly he's back to his original self, and alive, at level 31. There's simply no creativity here. I get that The Fall of Truth seemed to end the original storyline, so why not a new end boss? A Slaad perhaps.
LTS is supposed to drop LGS mats, so why not at least have some sort of tie-in? Thematically, it doesn't make sense for LTS or LHoX to drop mats, with no storyline involvement. They just seem like filler quests, by simply making them harder and adding nothing else. Even if LTS gets delayed for a future patch or Update, I'd be okay with it, as long as things are actually changed. Devs, please give us something more than just the same quest with more damage and more hit points. Please.