Transitioning from ARR gathering to timed-nodes was a huge adjustment and at the time I hated it. The idea of having to be in the right place at the right time, and hope my skill was enough to extract the resource, was a massive pain in the butt. These days we have things like Garlond Tools to tell us when and what, and the collectible menu that's dramatically improved the process made it a lot less painful. Being one of the people who love(d) crafting and being a self-sufficient omnicrafter/gatherer capable of making all but the highest-end items, this change really pissed me off and I stopped engaging at the levels which required items from those timed nodes, never to look back. I'm still an omnicrafter/gatherer out of habit and enjoyment of the "slow life" game play, but I've never engaged in higher end stuff to make money with since.
The advent of positionals being a significant thing was another major adjustment. Having to get behind or to the side of a boss based on skill procs increased complexity quite a bit. Coming from ARR where things were a bit more static and mostly revolved around hitting your rotation and avoiding what we would consider today to be easy mechanics and moving to a more location and proc-based game play took a while to adjust to. The increased difficulty of dungeons and raids only compounded that. Some felt this was a major improvement due to increased engagement with a fight but others saw it as a too-steep increase and railed against it. Ultimately, SE chose to decrease difficulty to a relative sweet spot.
My happiest memories of HW are character story based. When I made my guy, an Elezen Dragoon with the Fury Matron, HW wasn't even in the public eye. Going into Ishgard where all of those major aspects of my character were front-and-center was MASSIVE for his story development and increasing my attachment to him. The only way I could have made the situation better was to have rolled him as a light-skinned, rather than grey-skinned guy so he looked like the rest of the characters.
Then there was the music...aside from Unchanging, Ever-changing in ShB, the music from HW is my favorite, way above all the others. Night in the Brume, Painted Skies, and Contention are on all of my Orchestrion play lists.