This book provides an excellent treatment of PDEs for (pure/general) mathematicians. If you are interested in PDEs, you should definitely consider reading this book (albeit this book requires 'active reading' with pen and paper as parts of the proofs tend to be left as an exercise for the reader). The first part introduces various methods to find classical solutions of certain linear and nonlinear equations (separation of variables, characteristics, transform methods, similar solutions, Green's functions, power series, etc.). You should be familiar with vector calculus, parametric improper integrals, the Fourier series and ODEs (among others) to fully appreciate this part of the book. The second part introduces Sobolev spaces and analyzes the properties of weak solutions of second-order linear elliptic, parabolic and hyperbolic equations. The third part introduces techniques to tackle nonlinear equations (the calculus of variations, fixed-point theorems, nonlinear semigroup theory, etc.). For these parts, functional analysis is necessary. Not much measure theory is generally required except for the theorems for changing the order of a limit and the Lebesgue integral (the appendix contains the bare minimum on functional analysis and the measure theory).
The book is a great choice if you want to learn how to prove the (non)existence and uniqueness of (classical and weak) solutions, analyze their regularity, derive certain bounds and so on. However, if you are more of an applied mathematician looking to learn how to actually derive mathematical models of real-world phenomena with PDEs or if you want to study specific parts of (applied) PDEs like reaction-diffusion systems, traveling wave solutions and their stability, steady-state solutions and their stability, dispersive waves and similar concepts, then you will probably be better off with different PDE textbooks, such as those by Logan, Debnath or Haberman or even with an applied textbook (like Murray or Kot for biology).