First, I agree with a lot of what has been said in other reviews. It seems the author has gone out of his way to not bother explaining why any of the material sandwiched between the covers has any relevancy in the real world, let alone trying to design a circuit from scratch. Thus I found myself simply not caring about the material, and just cramming in facts before a test. However, after briefly beginning to read another book on the subject (Fundamentals of Microelectronics by Razavi), I can see everything that is wrong with Sedra's work and everything that is right with Razavi's. For example, the main reason for reading microelectronic books is to understand how BJT transistors operate. Sedra will have you religiously chanting Vbe = .7 V, and Ic = B*Ib. However, knowing these two facts does little more than give a false sense of security going into exams, and even the slightest hiccup in a given problem will cause you to become completely lost or forced to run around in an infinite loop of logic (well this must be this but it can't be that because this has to be this but because this is that...). Simply put, there's a thousand different problems you can be asked involving any concept in this book, and without an intuitive understanding from "the ground up", which this book does not provide, you're screwed.
If I were to reduce the first paragraph to a single analogy: If this book's job were to teach you how to drive a car, Sedra would tell you about how to refine the engine oil, calculate the wear on your tires, and why the gas pedal is at a 60 degree angle. But you still don't know how to drive a car.
Then we look at Razavi's explanation where he starts from the beginning explaining that the *reason* we're bothering with transistors is because they act as voltage controlled current sources. I read Razavi's book after getting an 'A' previously using Sedra's book and was amazed at this simple explanation that had eluded me before. Contrast to Sedra starting off by spending 30 pages explaining the physics of a transistor and migration of holes and electrons across widths with drift currents blah blah blah (I've fallen asleep at this point). Razavi immediately shows various amplification designs and provides clearly reasoned explanations for the pros and cons of each design. You understand what biasing a transistor really means and make intuitive conclusions of your own will, whereas this book will have you acting like a robot plugging in numbers and "magically" everything falls out. And Sedra doesn't even bother talking about using a transistor as an amplifier until halfway through the chapter (which is treating the most important function of transistors as a side note!).
Other grievances with this book are the examples are incredibly simple whereas the end of chapter problems are insanely difficult. For example, the diode chapter will have an example dealing with 1 diode and 2 resistors and a chapter problem will have 6 diodes, 20 resistors, an op-amp, and a transformer all in one (slight exaggeration, but this is what it might as well be most of the time when you look at a problem and sit with no idea where to even start). This book makes liberal use of words like "obviously", "of course", "it is clear that" which leaves a reader little more than frustrated and confused (we're students, we want and *need* hand holding). Furthermore, there's dozens of equations being "worked out" where the author skips a few steps and forces you to think and stare to figure out what he did (still feeling lost even if you figure it out). Frankly I'm amazed that after reading hundreds of pages from this book I could have managed to learn so very little. The overall layout (boxing equations, headings, etc) is pretty good, but the order of presentation and emphasis of concepts is terrible.
To wrap this review up, this book seems to have been written by the type of professor who shows up to class and reads notes he wrote 20 years ago. He never bothers to talk to students, stop for questions, or hold office hours, and it reflects in this text. I recommend Razavi's book much more readily than I recommend this one, but chances are if you have to buy this book then the professor will make (useless) exam questions that Razavi doesn't directly answer (if it's not useful in the real world, he doesn't talk about it), so you'd have to use both. I'd suggest reading Razavi's book thoroughly first and the glossing through this one (or selectively using it as a reference).
In short, this book largely seems to have been targeted to someone who already has a thorough understanding of various microelectronic topics, and doesn't want to be slowed down trying to carry you. However, this book does contain topics and diagrams which other books might miss (this book is heavy!) so it makes for a decent gap-filler.
PS - I have both the 5th and 6th editions of this book. The 6th edition does little more than combine all the "Frequency Response" sections from chapters into their own dedicated chapter (which Razavi has done from the start), add a few problems to the end of chapters, and copy-paste the 5th edition problems (with changed numbers to prevent reusing solutions, which in my opinion is low). There's a little bit of reorganization + re-titling elsewhere and a few equation summary tables added, but most of the content is the same.