In my battle for holiness I've bought and read a stack of books from all through church history. Many of them are excellent and well worth your time and money, but there are at least three ways this book surpasses them all.
1) It is dead simple. John Owen on sanctification is fabulous, but people thought he was hard to read in the 17th century, and he's not got any easier since. Chester has clearly taken in much of the wisdom of Owen, Ryle, and many of the other classics and restated it in language which is racy, gritty, true to life and simple. I would feel confident giving this book to a new Christian who'd never taken A levels - many books I've read would be a challenge to a university graduate.
2) It gives a great overview. A remarkable number of great books seem to specialise in one or another thing but don't give an easy vision of the big picture. While Chester doesn't go into the depth that other books sometimes go into he's by no means superficial, at the same time giving an insight into the wider battle with unbelief and idolatry.
3) It's relentlessly gospel focussed. There are other books that do this, but it's so important that it's got to be mentioned really. Without ever being soft on sin, Chester never resorts to guilt-trip, or legalism to encourage you to holiness, because it doesn't work.
All in all, very much worth your money. I've read it four times now and still expect to get more out of a few more readings.