Sharn is the largest metropolis not only on Khorvaire, but on all of Eberron. It is built on a relatively small piece of land at the mouth of a major river. It is located in a 'manifest zone', which means the barriers between it and another plane - one attuned to Air - are thin and so magical spells using that element are stronger. This allowed enormous towers of stone to rise up as high as a mile. One neighborhood, the Skyway, is an island that floats high above the rest of the city. The high population is mixed as well, with all of the traditional races of humans, elves, dwarves, gnomes, halfing and half-orcs, but also a substantial minority of 'monster' races from goblins to medusas make their home here.
This makes for a complicated setting. The towers grow so high lower levels are sometimes in complete shadow, despite the presence of everbright lanterns, and there are rumors of older ruins deeper in the foundations of the city. Skycoaches or public lifts easily bring residents or visitors anywhere they like, but a notoriously corrupt city watch and several active gangs in all levels of power can make the city as difficult to navigate as a dungeon.
The book separates the city into levels, districts and wards and spells out what adventurers will find there. Everything is considered from entertainment districts to residential working class neighborhoods. There is even a section on local government and a nod towards such things as sewer systems and zoning permits. Love the details.
I'd used this extensively during my long Eberron campaign, but reading 'The Night of Long Shadows' made me remember that I'd never read it cover-to-cover. The truth is, as handy as it is, it just doesn't feel like enough for a separate book. The CD of atmospheric music is a nice touch, but not what I was looking for. Sharn is simply too enormous to go into the 'Eberron Campaign Setting', but there should have been a module or two, bigger maps, or something else built in for added value.