Brandon Sanderson had a very interesting plan for the Mistborn world.  Why is all Fantasy locked into the time-frame of sword and sorcery?  To prove it doesn't have to be that way, he fast forwarded three hundred years after the Mistborn trilogy to the equivalent of our 1800s.  Railroads are just coming of age, and are now the most economical method of shipping goods.

Well, it would be if thieves weren't stealing the most valuable shipments.

Lawkeeper Waxillium "Wax" Ladrian is forced to give up his wild-west sheriff lifestyle after his uncle dies, to move back to the city and keep afloat their nearly bankrupt family estate and business.  Try as he might to avoid it, a mysterious string of train robberies by "The Vanishers" pulls him in.

The Alloy of Law, as a successor to the Mistborn trilogy, contains the same rules for magic: Allomancy, Feruchemy, and Hemalurgy.  It's interesting to see how somewhat rare magical abilities are still a part of this world.  Wax is a "Twinborn", which means he has one aspect of Allomantic power and one aspect of Feruchemy.  In this case he can "push" metal and adjust his weight.  Being Twinborn is common enough to have names for all the possible pairings, but is about as good as it gets.  By this time, Mistborns (who have access to all Allomantic powers) are unheard of and considered mythical.

I really enjoyed this novel because it's not your usual fantasy, and furthermore is a mystery.  Who's doing the robberies, and why?  How are they accomplishing it?  Why are certain shipments being targeted?  I got so wrapped up in the final conflict I forgot about the bigger mystery, so was quite pleased when the layers were revealed, thus setting up the next book.

Do you have to read the Mistborn trilogy first?  Not really.  Sanderson explains each aspect of magic as it gets used, and really, there's only a few types presented in the story.  If you intend on reading the original trilogy though, it would probably be better to do so first.  Events from the trilogy are referenced in this story, so read the trilogy first if you want to avoid spoilers.

The Good: Likeable characters.  Solid story telling.  Interesting twist on Fantasy formula.
The Bad: Epilogue reveal seems a bit... contrived.  I don't understand the motivation for the villain's first step in the master plan.
The Ugly: Can't think of anything to put here