Elantris is a city of magic, living gods, and very few logical explanations. The city is literally made out of magic. Then one day it fell apart, the gods lost their powers and became cursed, and yet no one could figure out what happened or how to restore the magic. Elantrians are a people that kept a record of everything that ever happened in the world and no one thought to consider the giant rift in the land to be the cause?
Sanderson's settings are often disordered, both politically and physcially. Elantris, following the fall, is left in various states of decay, sectioned off from the rest of the land, and covered in slime. The physical descriptions are vivid and quite disgusting, and the events happening within the fallen city, to me, is possibly the most interesting part of the story. Raoden's attempts to restore life to the post-apocalytpic dystopian society is admirable, like a true Sandersonian hero. That he succeeds in pulling the population together in just a few weeks is... unlikely.
One of the few shortcomings of the writing is that the characters are presented as either "good" or "evil"; only one ambiguous character straddles the line, Hrathen. But he thinks he's working for the good of the world and saving people's souls while preventing a hostile takeover that could lead to bloodshed. So technically he's "good." Sort of. Maybe...
The magic system is one of the most interesting I've ever read. It may not seem like much at first, what with drawing signs or glyphs in the air and pushing at them to activate, but when you get to the big reveal near the end, it connects all the missing pieces of the Elantrian mystery in an unexpected way. Unexpected, but not unbelievable. Though I'd like more of an explanation than "the aons are part of the land and that is why the magic works." But what's special about the land that makes the magic work?
The religious aspect of the story is quite convoluted and is responsible for many of the info-dumps, I think, which drags the narrative down. We only get vague explanations of why Fjordell is such a war-mongering country intent on converting the world to their religion. According to Sarene, converting to and living under the Shu Dereth religion of Fjordell is one of the worst things ever, but that's only stated, not explained or shown. It's also stated that Sarene's homeland is one of the best free cities in existence; again, only stated, not shown.
As for plot twists, they're really good, but I got the feeling that some of them were thrown in to throw the reader off track, which a few of them succeeded, like the whole Dilaf thing and the real reason for his hatred of Elantrians.