It was one of the most heartbreaking experiences. After investing years mucking around on the Aus-1 server for Brood War and years grinding my way up the South East Asian, Korean and North American ladders in Wings of Liberty, Heart of the Swarm killed StarCraft 2 for me.
I simply couldn't play. The physical stress was already a substantial burden. But it was more than that. The game had ceased to be fun. The campaign was less of a joyride too. And the many problems that existed with Wings of Liberty were still present.
But Legacy of the Void has corrected many of those. I'm enjoying myself again. I'm looking forward to matches again, and I'm not the only one.