I read the first book in the Mistborn series, Mistborn: The Final Empire, about six months ago and I found it to be a brilliant read. The Well of Ascension is quite a different book to The Final Empire in some respects - the pacing is slower for the most part and it's more focused on the character development and political intrigue - but it's an enthralling sequel to that book and is probably one of the best sequels that I've ever read! All of the characters from the previous novel that are in this book get huge development (especially Elend, Vin, Sazed and Breeze), we're introduced to some highly intriguing new characters (Zane, Tindwyl, Allriane and OreSeur), and we get to learn a lot of fascinating new information about the kandra and the koloss. There were also three or four separate plot twists that were so clever and unexpected that they literally made my jaw drop! :D
One of the other things that I'm especially loving about this series right now is seeing how Sanderson is able to take these certain typical fantasy tropes and then be able to subvert them in creative and imaginative ways. For example one of the most interesting aspects of The Final Empire was that we were kind of able to get a sense of what Tolkien's Middle-Earth might have become if Sauron had actually won the War of the Ring, whereas in this book we now get to see what the consequences of overthrowing an evil despot are. In fact it's only now after reading this book that I realise just how shockingly under-explored it is in fiction! Usually we don't get to see very much of the consequences of a revolution at all in fiction apart from the immediate happy celebrations but that isn't the case with this book at all. Because even with the Lord Ruler gone things are still pretty awful in this world and in some ways the world is an even worse place.
I'm not planning on reading the next book in this series immediately but I certainly don't intend to hold off on reading that book for as long as it took me to get around to reading this one. The Well of Ascension was a fantastic read and it's hard for me to say which of the two Mistborn books that I've read so far is better. I did really miss Kelsier in this one of course so I think the first book may have the slight edge but there's really very little to separate them in my mind. If the third book is able to match their quality then it will easily go down as one of my favourite fantasy series.