'"Alloy of Law" follows up about 300 years after the events of the Mistborn trilogy. I enjoyed it overall. It's a much quicker read than the previous Mistborn books, it's less philosophical, and it's more focused.
It still has interesting tidbits, though. One exchange discusses trust:
"Propriety is nonsense... Too much in high society is built around the idea of making sure you don't need to trust anyone... Contracts, detailed operating reports, not being seen alone with an eligible member of the opposite gender. If you remove the foundation of trust from a relationship, then what is the point of that relationship?"
On the one hand, removing trust from an equation can simplify things, and the point of the relationship can be any number of things. On the other hand, trust, and strong relationships in general, make things a lot more smooth and enjoyable for all involved.
While the novel is, in theory, a standalone, I wouldn't recommend it to someone who hadn't read the first trilogy.