Alloy (n.) (Paraphrased from American Heritage and Webster) 
 1. A homogeneous mixture or solid solution of two or more metals. 
 2. A mixture; an amalgam: "A combination of epic fantasy and western" 
 3. Anything added that serves to reduce quality or purity. 
 4. (v.) To debase by the addition of an inferior element; adulterate. 
 I think it's probably a good read, if westerns, 1950s-style protagonists, and admixture continuations are your cup of tea. Personally, I like stories to end. I genuinely enjoyed Mistborn, and I thought the trilogy had drawn to a satisfactory conclusion. For me, these types of mixtures and additions only diminish the value of the original. 
 ...And that's all I'm going to post here. 
 The rest of my (rather verbose) review is posted over here at Booklikes. 
 Why? Because I disapprove of GoodReads' new policy of censorship, I am no longer posting full reviews here.