I might be late to the party, but Thaldrazsus looks incredible. I can already say that - for me - it's one of the most beautiful zones in WoW and its diverse biomes and architecture is just fantastic. It's a masterclass of zone design and the art department really delivered. Where Shadowlands - while it had great zones - looked pretty bland, Dragon Isles is so full of Warcraft nostalgia and it's oozing just the essence of what made WoW so great in its first years.
The Dragon Isles really feel like coming back home, from an immersive point of view and that's something they said they wanted to do and I can already say they pretty much nailed it visually.