From the reviews:

...Lang's present book is a source of interesting ideas and brilliant techniques.

Acta Scientarium Mathematicarum

... It is an admirable straightforward introduction to calculus.

Mathematika

A First Course in Calculus went through five editions since the early sixties. Now the original edition of A First Course in Calculus is available again. The approach is the one that was successful decades ago, involving clarity and adjusted to a time when the students' background was not as substantial as it might have been. ... The audience is intended to consist of those taking the first calculus course, in high school or college. (G. Kirlinger, Internationale Mathematische Nachrichten, Vol. 57 (193), 2003)

This is a reprint of the original edition of Lang's A first course in calculus, which was first published in 1964. ... The treatment is 'as rigorous as any mathematician would wish it' ... . There are quite a lot of exercises ... they are refreshingly simply stated, without any extraneous verbiage, and at times quite challenging. ... There are answers to all the exercises set and some supplementary problems on each topic to tax even the most able. (Gerry Leversha, The Mathematical Gazette, Vol. 86 (507), 2002)