Sharn and Waterdeep are approached very differently. Waterdeep provides an extremely detailed map, then develops a large number of specific locations on the map, showing exactly where they are. Street names are specified, and you can look at the maps and see exactly where things are, just like a real-world map.
The Sharn book, on the other hand, is set up to provide the tools and information you actually need to run a game in Sharn, but it carefully avoids giving the detailed information found in Waterdeep if it would detract from playability. For example, the maps are fairly general, showing where districts are in relation to one another, but no actual "streets" are shown - even the "towers" shown on the maps could be accurate or could be representational, depending on how you want to do things. A number of specific shops, inns, temples, etc, are detailed, and I thought there was a lot of interesting material there and a good balance of the sorts of things adventurers would actually look for or get involved with.
If a specific restaurant or shop is listed, you only know it's in a specific district, not where in that district it is. On the other hand, simple guidelines are provided for how long it takes to find a particular place - the Gather Information DCs required to locate a place, the amount of time required based on how where you start (same district vs. nearby district vs. other side of the city), and the amount of time you trim out if you're willing to ask for directions as you go. If you want to find a certain type of place, such as a store that sells a particular type of item, there are simple rules for determining whether a given district includes such an establishment.
The system used for defining and detailing each district is a slightly modified version of the city creation method found in the DMG Web Enhancement, so take a look at that to see if you like it, or if it annoys you - but it works better in Sharn than I ever expected from just reading the web enhancement.
The book also spends a lot of time on important people in the city, and (more to the point) the various ongoing conflicts between different groups of people. If a PC is from a specific nation of Eberron, there will be places in Sharn where this will be a benefit, and places where it may be a liability. Specific races likewise will find allies and enemies ready-made. Plenty of potential plots can be found in the political situation, the rivalry between a couple of major criminal organizations, the pro-warforged vs. anti-warforged factions, and so forth. And all of this felt extremely real to me as I read the book. Nothing felt like it had been forced into place because someone wanted to fit it in - everything felt like it belonged, like it came from the established history and other details. That also, incidentally, helps make it much easier to get a grasp on where to look for things.
I also liked the fact that it felt like a real place which had developed over time. You can see where the rich people used to live, and how as "undesirables" got closer they built more, higher places to move to, just like the development of real cities.
My very favorite single item in the book was the description of how the common folk who belong to the Blood of Vol interpret their religion. Few gaming settings bother to make a religion that has any realism or depth to it - this one creates a setup in which good people can convincingly belong to an "evil" faith and not be evil at all. Very, very cool. (Similarly, the issues between the LG church of the Silver Flame vs Lycanthropes gain some real depth in this product.)
The downside - the material in this book really does require the Eberron setting to be used if you want to get the most out of it. So much of the inter-group rivalries depends on Eberron history and cultures. You can certainly find plenty of ideas to borrow if you use other settings, just understand that you'll have to develop many more of your own plot-hooks etc. if the Eberron setting doesn't fit your needs.
Also, there are some unfortunate editing errors, mainly tied to the maps, that require a small amount of extra effort on the part of anyone wanting to use this book. First, no bridges were shown connecting the Plateaus, nor were any mentioned in the text, yet the text implies Skyway is the only part of the city reachable only by flight. (If you go to the WotC site, into the Eberron section of the messageboards, and into the Ask Keith Baker FAQ, on page 4, search for the word "Bridge" and you can find his recommendations for where such bridges should be located - he said there that he hopes to make this official with a Dragonshard article soon...)
Also, the Middle level map has two mislabeled quarters - don't have the book with me, but I think it was Platinate and Den'iyas (sp? the one that is also known as Little Zilargo), which are really Upper Level quarters, and you need to derive which two names really should be on that map from the text (Smoky Towers and Little Plains, I think, but that's from memory) - but which is which? In Smoky Towers there's a bit of text referring to the quarter directly below it, and it's actually a typo combining the names of the two possible candidates. Sorry, without the book I can't be clearer, but my best guess after struggling with it is that Smoky Towers goes over the Entertainment district on the lower level, and that means Little Plains doesn't go under Little Zilargo, it goes under the other one. (There are also a couple of districts with their names misspelled on the maps, one in the northern plateau with "-gard" instead of "-yard" and the other written as one word in the text and two words on the map, can't remember the actual names of either of these, though.) These are minor quibbles once you sort them out, but still irritating.
And what's the deal with NO INDEX??? I'm making one, if no one else beats me to it...
Ultimately, despite the lack of map editing and index, I think the Sharn book was one of the best products they've put out in a long time. I enjoyed the whole thing, and it gave me plenty of ideas for how to improve the way I develop fantasy cities of my own.