Although Hartley's book offers a deeper perspective on stereo 3D reconstruction, it is also aimed at an audience with a higher knowledge on this area, both mathematically and conceptually.
This book on the other hand offers a more simplistic solution but it also offers a good review on disparity and point correspondence estimation, which on Hartley's book is barely covered.
As each of theese books offfers a slightly different point of view on the matter, I suggest having both as good references on the subject.