Disclaimer: I've only read the original trilogy and part of the first book of the second trilogy.
Mistborn is a series of fantasy novels by Brandon Sanderson that boasts some cool worldbuilding and probably the best and most creative magic system I've ever seen. The premise of the magic system is that cerain people can digest small bits of metal and then "burn" it for a magical effect depending on the metal. The books (the three that I've read) have a strong plot and are well-written, and the first book is even emotionally powerful, but I would ultimately not recommend the series. The main reason is the endless moral bullshit in the second and third books. Still, the first book might be a worthwhile read, and I won't blame you if after reading it you refuse to take my word that the next two are bad. Here's my list of objections (I'll mark spoilers):
When Vin and Zane go into Cett's tower to kill him, they slaughter hundreds of guards who are just following orders and are probably being coerced into fighting for the wrong side, then, when they get to the one person in that building who is actually both evil and an active threat to innocent people, she spares him. What the fuck?
When Elend murders Jastes. Make up your mind, Brandon Sanderson, is killing wrong or not? And even though I believe in Retributory Justice, I don't extend that to repentant sinners, which Mr. Sanderson apparently does (when he feels like it). Besides, isn't there at least a chance that Jastes could still stop the koloss from attacking?
That Spook and the others don't just take down Quellion. The characters even discussed it and said they didn't think it would work because "we don't have Kelsier anymore", but it was painfully obvious the real reason was that Sanderson's morals had changed, and he no longer believed in forcefully overthrowing oppressive and murderous rulers. And much worse, the statement that the city somehow got lit on fire because the revolters were too angry. Seriously, Sanderson? Anger magically lights things on fire even when you don't want it to? I don't care if this is fantasy, you still can't get away with that.
How Ruin (appearing as Kelsier) tries the I Will Give You Power If You Kill Him ploy on Spook. Aside from the fact that Quellion deserved to die, contrary to popular belief, power is something goodguys should seek, not avoid, and nobody in this world needs to hear how evil and corruptive power is.
Actually there was another more minor case of this in the end of book two when Vin decides to give up the power at the Well of Ascencion, but I didn't make that a point here because Sanderson gave that choice bad consequences so it didn't look like he was advocating it (although I'm sure he was).
That lord Yomen is portrayed to be a good person on the inside, just misguided. Nobody who believes in the Lord Ruler's policies can be a good person, period.
That the "goodguys" are a government in the second two books.
That those "goodguys" have a habit of putting peviously defeated badguys in charge of parts of their empire: Janarle, Cett, etc.
The only problem with book one: that they don't immediately tell Vin about Feruchemy and Kandra. The whole story is about trust for god's sake. The commonly-given excuse in fiction for keeping secrets from allies that "what if one of us gets captured" is bullshit.
It was really disappointing that he had Vin kill Zane in the end of the second book. I would've much preferred to see him join them, because I had been made to sympathize with him. He wasn't evil and he didn't deserve to portrayed as such.
Atium is logically impossible because you can't know someone's decision before they've made it. It's not as bad as full-fledged time travel, though.