I use C because I think that it is good (some improvements could be made, but the other programming languages which try to make C better tend to make many things worse in my opinion; I like many (but not all) of the features of (Digital Mars) D, though). I think that the worst feature of C is the confusing syntax for types. (Maybe the way to make a better one might be like "LLVM with macros", although there are a few problems with LLVM too.)
Some compilers and libraries, such as GNU, do have some improvements. For example, in GNU you can make zero-length arrays (which I use sometimes), ?: without anything in between (which I use often), and some other things.
They say there is no object-oriented programming in C. Well, C doesn't have object-oriented features, although you can still do some limited object-oriented stuff in cases where it is useful. For example, there is the stream object (called FILE); GNU has a fopencookie function to write your own implementation of the stream interface too, even though standard C doesn't have that.
Object-oriented programming is good for some things but too often is overused in modern programming, I think. You shouldn't need object-oriented programming for everything.
It is true that some of the undefined behaviour stuff is too confusing and perhaps should be changed; in some cases the compiler has options to control these things, such as -fwrapv (which I often use).
I like the string handling of C; you can easily skip some from the beginning, and can sometimes use the string functions with non-text data too, and it doesn't use Unicode.
It says "C lets you take the address of any variable you like", but this is not quite true. There is a "register" command which means that you cannot take the address of something.
I think that many things in C (both things that they mention and some that they don't) (including pointer arithmetic, no bound checking, untagged unions, string handling, not using Unicode, setjmp/longjmp, etc) are often advantages of C.