Since The Alloy of Law is sigificantly smaller that Sanderson's other books, it's understandable that it feltlacking in some places. There wasn't as much going on, which meant there wasn't enough build up or development for me, which meant I didn't spend enough time with the characters to really fall in love with them. That said, I still really enjoyed the book, and I'm so happy that Sanderson is continuing to write in the Mistborn world.
I love how everything has progressed since The Hero of Ages. Vin and Kelsier have become legends, and *grumbles* so has that other guy. I missed them all so much, but I loved how often they were mentioned in such a short book.
I missed the original characters almost too much, though. I liked Wax and Wayne, and I totally ship them, but I miss Vin. A lot. And Marasi wasn't enough to make up for it.
I also loved how the Allomantic powers have progressed and evolved over the past 300 years or so. I'm not going to go into detail but that was something that I loved discovering, and I can't wait to see more of that in the sequels.
Basically, I really enjoyed The Alloy of Law because I love the Mistborn world and I can't get enough of it. I just need to learn to let go of the past because I am still unable to completely forget (or, rather, move on from) Vin, Kelsier, and the others.