In many ways, introductory calculus is a difficult subject to teach properly. Calculus is in a bit of a difficult place in mathematical pedagogy; it is a subject of paramount importance with broad application to nearly every natural science, yet a rigorous treatment is difficult to provide at a simple level as the theory is far more complex than meets the eye. Typically engineers and applied scientists will never need to see the inner workings in substantial detail (and most never do, unless they take courses in real analysis), yet this can at times provide a frustrating lack of clarity on the motivations and derivations of calculus. I have read a few calculus texts, and I have found that texts written for a first introduction are either at a level of too much handwaving (such as in Stewart's calculus) or of too much detail for a typical student without a background in mathematical proof (most analysis texts). I believe this text does a good job at teaching calculus at a level appropriate for a first introduction, yet with enough additional detail and optional proofs in the exercises to come away from it with a more satisfying understanding of some of the workings under the hood. For example, some of the exercises in this text do a good job of going above and beyond by guiding the reader through the derivation of Stirling's formula, the gamma function, more difficult methods for integration, and applicable results. Some chapters are not as complete as others, and other texts would be more appropriate (in the case of exterior forms and some of the vector calculus content). Overall, I would recommend this textbook as an excellent first introduction to calculus with enough difficulty and detail to remain interesting and provide a satisfying explanation for non-obvious results.