Heavensward is a big step up from the original "A Realm Reborn" story. It features new areas, items, level 70 cap, voice actors, and other items and collectibles. The endwalker pack has every DLC pack released into one which is really convenient for those who are willing to grind jobs to level 90.

One addition I did not like is the mount flying lock behind some quests and finding aether points to activate. It just makes doing quests annoying when you can't fly and have to put extra work.