I was worried to pick up another widely celebrated fantasy author after my George R. R. Martin "Waterloo".
Brandon Sanderson luckily is far from that category - although I'm not all hyped about him yet either.

What I did like and adore about this first book of his Mistborn-trilogy, as many people, is the magic system. I find it clever in how it regulates the power of those able to access magic to prevent the emergence of unbeatable (and thus implausible) "superheroes". I am somewhat worried that Vin might turn into an overpowered character despite that, though.
Also, I did enjoy the world- building, including the excursions into myths, legends and fragmentary "memories". I could bear with that even though it felt like 75% of the book with the actual story slugging along as a side note for that part. When the story got into focus (finally!), it was mostly amazing. 'Mostly' because I felt that there were those moments when the author chose to shake something from out of his sleeve instead of taking the time to build a "proper" solution that didn't rely on the reader's blind acceptance as much.

As for the characters - of which there were quite a lot with quite few females:
Sadly, most characters felt flat to me and weren't able to make me care. One character actually managed to annoy me quite a bit: Kelsier. As a former online roleplayer, it never fails to raise my hackles when characters hang about on rooftops with their coats or cloaks billowing out behind them dramatically in the breeze while they gaze into the distance thoughtfully. And he does that. A lot. Also, Kelsier generally feels like he got all the cool attitudes and action hero lines Mr Sanderson's roleplaying characters never were allowed to use in his pnp rounds for fear of an annoyed dm dropping an angry gargoyle on them. I'm almost ashamed to say it, but my feeling upon his death was relief (in the hopes that death is more reliable in the Central Dominance than in Westeros).
But: There were two and a half characters I could dote on and obsess over enough to make me happy. And one of them even is the mainest main character of the lot, Vin. I enjoyed watching her character development as much as discovering Allomancy with her, I feared for her and with her, and I was overjoyed to find that, apart from logical restrictions due to her story line, she was well able to look after and think for herself. She is the main reason, apart from the interesting world as such, that I'll read on at some point in the near future.
The other character who I took to is, of course, Sazed. Who could not love a figure whose basic concept is that of a walking library while being so benign and kindly about it? Feruchemy seems an almost better concept than Allomancy, and his background story is fascinating and horrifying at the same time.
The "and a half" is the kandra. I need to learn a lot more about that fascinating kind of creature...

I was not overly excited that Vin had to get a love interest, though I guess, for some reason, you have to have that in books for anyone over the age of 12... and I'm completely fine with the lack of sex scenes here. At least that bullet of potential corniness was dodged.

So, all in all, a promising first part with no faults that might not be "redeemed" by the other parts.