While he was mostly on the side of evil, I did like his unique character. For example, he’s changed sides more times than people remember. He was once a maester who got kicked out of the order for dark experiments. He survives a Lannister attack in the Riverlands and ends up in the care of House Bolton. But he leaves with Jaime to King’s Landing, where he vows allegiance to King Joffrey.
But he spends way more time being a minion of Queen Cersei. You see his passion for “science” when he “heals” Ser Gregor Clegane after the trial by combat.
And turns him into a semi-zombie thing. Which earns him a place in Cersei’s heart. Having a nearly immortal soldier at her side at all times, made her protected from her many enemies. Qyburn quickly assumes a top spot in the Small Council.
And following Tommen’s death, becomes Hand of the Queen when Cersei claims the Iron Throne for herself. He was a pretty competent Hand of the Queen. Not many could do better at keeping Cersei in power.
But all of it goes to waste. Before Cersei’s own demise later that day, he’s squashed by the Mountain for commanding him to not fight his own brother, the Hound. While it happened quickly and not so dramatic, it is rather ironic he was murdered by the very monster he created.