I thought it was an excellent and satisfying ending. The story was concluded well. The final boss fight was intense, and very well done. There were a number of callbacks to earlier parts of the story. FFXIV also spent a fair bit of time on the denouement/epilogue, winding down the story nicely.
This is actually an area where a lot of MMOs and videogames fall down. The climax comes right at the end of the game with a final boss fight, and then the games ends, maybe with an NPC congratulating you. I really like FFXIV's approach of taking its time to wind down, showing consequences and outcomes for the major NPCs.
All in all, Heavensward was an excellent expansion and storyline. I've mentioned this before, but it's ironic that it took a Japanese game to give us a classical story about knights and dragons.