Brandon Sanderson has been one of the the best of modern fantasy fiction writers. I have a particular affection for The Rithmatist which has become one of the handful of favourite books I keep re-reading. Otherwise, I greatly enjoyed nearly all of his books (especially the Mistborn trilogy) yet without wanting to re-read them - with the exception of Warbreaker (2009).
I have read Warbreaker three times so far; and it is a really good book - ranging across humour, adventure, horror and with several scenes of great beauty and heart-warming heroism which do not fail to make me weep.
The characters are excellently done; varied, interesting, many are very likeable (even some of the baddies) - several are (in the end) genuinely, memorably heroic.
It displays Sanderson's supreme ability to invent many and different, complex and interesting magic systems. This remarkable system (based on 'breaths' and colours) has an extra symbolic level, with moral and aesthetic aspects.
He also invents a linked religion; which is unveiled through the plot. And the plotting itself is a real virtuoso effort - as intricate and satisfying as the best whodunnit detective novel - and like writers in that genre Sanderson springs his plot twists honestly; having explicitly given the readers everything necessary to predict the surprise - but misdirecting us from the implications.
Indeed, I have never come across any writer who is more adept than Sanderson at the plot-twist - and there are many in Warbreaker. This is linked to the fact that when Sanderson is at his best: nothing goes for nothing.
The reader needs to be alert and attentive from the first sentence; because everything has a payoff later (mostly, in some unexpected way).
Warbreaker is almost certainly the best book Sanderson will ever write - because it uses the fullness of his character to the maximum.
A book cannot be greater than the Man who writes it - and Sanderson has not at any point been a Great Man like Tolkien and CS Lewis. Nor (to mention two of the best modern fantasy writers) is he a genius at the level of Susanna Clarke when writing Strange and Norrell, or JK Rowling when she was writing the Deathly Hallows.
(Genius creativity is fragile, and temporary - especially among women geniuses, who nearly always suffer labile weirdness or craziness; whereas only some male geniuses do.)
In a nutshell, Brandon Sanderson has been about as good as a not-genius, professional author can be; because the heights of genius accomplishment are inner-driven ('endogenous'), and a genius is almost-never a professional.
Also because "Branderson" is now several years into in what looks like a permanent and self-willed decline; partly caused by relentless over-production. Including by the (related) mechanism of pro-fiction-production. Nowadays, this grossly over-uses the input of others, including activist editors - leading to a kind of composition-by-committee - a process that purges individuality, and smooths-away the peaks, as well as filling the troughs.
And lastly from the incurably deadly poison of creeping political correctness. Brandon Sanderson was resistant to this, due to a devout Mormon upbringing; but like the CJCLDS generally (although further advanced) he is now keenly spiraling-down the vortex of Establishment-pandering Leftism.