Just finished this one, and it's one of the few books that's simultaneously provoked a "wow, cool!" and a "meh" response.
The book has Charlton's magic system to thank for its Cool Factor. Basically, all spells are written in language that has taken tangible form -- size, weight, color, the works. As such, there's a ton of fun puns and concepts in here. For example, the main character casts a spell in a purple-tinted magical language, which opens him to the accusation -- made quite seriously, mind you -- of engaging in "adolescent purple prose." To censure a magician is to prevent them from casting spells. Ghostwriting is when a spellwright casts a spell to create his own ghost. Likewise, a subtext is a spell that no one can see.
Just as fun for rhetoric nerds like myself, one of Charlton's spellwrights can tell another's identity by the high frequency of double appositives in their magical prose.
My favorite reference, though, comes when Charlton describes the perils of the Disjunction, where demons threaten to break the tradition linkage between signifier and signified -- a good dig at deconstructionism always makes my day.***
Also, another cool element is simply Charlton's basic smarts. The dangers of changing a word's spelling, for example, recalls the debate about evolution -- slight changes can be beneficial, some are neutral, but most changes create destructive disasters. Likewise, most of the characters are terrified of completely cacaphonic (nonsensical) languages, which strikes akin to the fears over posthumanism where "nature" is no longer a valid measuring stick. (Charlton didn't actually develop that theme, but I think some critical legwork could find the implications there.)
Unfortunately, and I hate to say this, despite all these cool things, I found Spellwright to be relatively off-putting. The plot is . . . okay, I suppose. Somewhat convoluted, and skim-read large swaths of text. The teacher-magician figure is moderately amusing but hardly memorable. Nicodemus Weal, the protagonist, is a rather dull "child of prophecy" without much personality outside his dyslexia. In fact, speaking of prophecy, I was a bit surprised at how much I disliked the author using that old fantasy trope. Although Charlton does attempt to do something slightly new with it (i.e., putting the whole idea in doubt), it was too little and too late for me.
So, an "A" in magical systems, a "B" in general world-building, but a "C" in plot and character.
Charlton also gets an "A" is Being Totally Awesome As A Person. Apparently, he overcame severe dyslexia as a kid with the help of fantasy fiction, graduated summa cum laude from Yale, and is now a doctor with several medical publications in addition to his Spellwright trilogy. The s.o.b. is even the same age as me, the jerk.
Incidentally, I checked out Charlton's website, and he has a cool blog post about language in Tolkien. It can be found here.
***Incidentally, nothing marks this book as fantasy like how Nicodemus Weal is excited to teach a group of young students "composition."