I never know what to do with comments like this. It's obviously not a beginner's book. At the very least, it assumes that you know C. If your response is "C is a small language. You can learn it by reading <some-other-thing>.", you're admitting that APUE is not a beginner's book. If your response is, "C is a small language. You can learn it by reading APUE itself.", then I call bullshit. Is it theoretically possible, sure. But is it a natural way for a true beginner to learn C? Certainly not.
What do you mean by this? You obviously have NOT read it. I have. I'm telling you it is a beginner book. It does not assume you know C or anything else. It has nothing to do with the size of C. Grabbed it off my bookshelf -- he starts off telling you how to login to a unix system. How advanced can it be?
This is literally the book that taught me the basics of C within a week -- the first language I learned (15 years ago). So it is definitely a beginner book IMO.
Edit: I will say, he does get into some more advanced things toward the end. Which is why I like the book.. he starts off very basic, and by the end, he's covered the basics of interprocess communication, shared memory, etc.
C Interfaces and Implementations (David R. Hanson)
Expert C Programming (Peter van der Linden)
I'm also a fan of C Programming: A Modern Approach (K. N. King) as an introductory book, but it's very different in intended audience from K&R. King is writing for students, and he assumes nearly nothing. K&R are really writing for experienced fellow programmers, I think. So it's an apples to oranges comparison. But King is certainly more modern. He includes a fair amount of C99 material. The writing can't compare with K&R. It's nowhere near as dense or elegant. But if you find parts of K&R a bit too dense and elegant, it's a good trade-off. (I used them both in tandem while trying to learn C this summer. It worked well for me. When King got too verbose, switch to K&R. When K&R lost me, switch to King.)