I found Sirensong to be a really nice, appealing first dungeon. Similar mechanics, very different feel, but overall a nice welcome.

Shisui is purely aesthetic but it's awesome for a nice quick run due to the second trash pull being manageable in one.

Overall: agreed.

But 65 dungeon and onwards are next level. Second boss of Bardam's Mettle is awesome beyond awesome. They're really changing things up this expansion!