Jamie and Cersei *Spoilers*
So I had some mixed feelings on their death. It was anti climatic, it robed so many characters a revenge killing on Cersie, and this made Jamie's redemption arch become completely meaningless. However, after thinking about it, it is actually a very fitting death for them. The Lanister twins were always seeking glory and the had risen to the utmost heights. Instead of dying in glory, they are buried in an unmarked grave, with no fan fare or greatness surrounding them, just cold stone and earth. Their great family all but snuffed out in a blink of an eye.
In some ways its very similar to how their father died, the most powerful man in the kingdom dies on the toilet.