Thank you so much for the welcome! I'm stoked to be able to talk about this. I have always remembered Mistborn as being one of my all-time favorites from my teenage years, and now that I'm reading the whole series, I don't know anyone else who's even heard of Brandon Sanderson. (Calls into question the company that I keep.)
So, let's begin. While reading The Final Empire, I ended up keeping my pen handy, because I encountered some minor discrepancies in the plot (and some editing mistakes with spelling/grammar/punctuation). I don't glare at pages looking for these things, I just catch them while reading. Don't judge me! Haha. It just helps alieviate my anal retention if I mark it and move on. Anyway... When I got into The Well of Ascension, I had lost my pen and ignored discrepancies until page 290 (hardcover), where chapter 31 ends as Lord Cett reveals himself in the crowd, wearing "a suit". The uptake of the scene in chapter 32, from the same perspective - that of Vin - contains a quote from her character: "He's not wearing a suit."
This is just one example of minor plot discrepancies of this kind. Not that big of a deal. I again stopped annotating the book shortly thereafter, having lost my second pen. However, it's these slips in the plot that drive me crazy and interrupt my immersion in the story.
There are some larger discrepancies, I think, in the last half of TWOA. I need to go back through and try to figure out exactly where (that is, if you kind people are interested in discussion on the matter).
I have started reading The Hero of Ages now, but I was hesitant because I felt that Sanderson took advantage of his own plot twists in TWOA:
The moment when Vin proposes to Sazed that the mists are, in fact, the Deepness disappointed me. It felt as though that passage was meant to be a striking culmination of the story thus far, but it seemed very obvious to me that it was a logical conclusion, and I had been expecting it for chapters and chapters. Not that I had it all figured out because I am oh, so observant - but that the writing up to that point seemed to make it obvious - not only for an observant reader, but through the perspective of Vin. There wasn't appropriate suspense, in my opinion, and it made me feel like I had eargerly read through that entire portion of the story only to be let down by the mid-plot climax.
By the end of the vollume, I was less fascinated than irritated with the resolution of the mysterious stolen sentence from Sazed's transcriptions. I know there was appropriate foreshadowing by means of Kwaan's, "I write these words in steel, for anything not set in metal cannot be trusted." However, that the resolution of it all was that the transcription had been totally tampered with by the mist spirit, or Ruin (as the opening of The Hero of Ages is starting to explain), but the metal etchings in Kwaan's original steel tablet were then re-rendered to their original form again... It just seems a convenience, and doesn't compell my curiosity very much. Why would the steel etchings, inside the Conventical of Seran, return to the original wording after Ruin has been set free? Why was the mist spirit able to rip pages apart, but not perform other corporeal communication to reveal the problem of the research?
These are only some of the things driving me nuts, but it's probably more than enough to start a conversation, right?