Gerard 't Hooft's "Quantum Field Theory for Elementary Particles. Is Quantum Field Theory a theory?" (Phys. Rept. 104 nos. 2-4 (1984), 129-142, author's eprint). This is a beautifully written review, with rather little in the way of prerequisites. From the abstract,
What I would like to point out is that renormalizability is just one step in an evolutionary process of quantum field theory. In order to illuminate this point of view I will present a survey of the evolution of quantum field theory into its present form. However we will not follow the historical development, but rather, for my convenience, the lines of logic. As is well known, that is quite something different.
't Hooft also has a longer introduction to the subject,:
The conceptual basis of Quantum Field Theory. Gerard 't Hooft. In Philosophy of PhysicsPhilosophy of Physics (J. Butterfield & J. Earman, eds., Elsevier/North-Holland: Amsterdam, 2007). author'sAuthor's eprint.
This reads more like a textbook geared at readers with fairly solid quantum mechanics and a good understanding of special relativity, and covers a rather wide range of topics, so it is a little more advanced.