In 1802 the Rev. William Paley, in his book, "Natural Theology", used the watchmaker argument as evidence for a designer (God).
"Suppose you are walking on a heath and you find a watch lying on the ground. You would immediately realise that this was the work of a craftsman and had been purposely designed".
He then went on to examine the complex structures in living things to argue that they must also have been designed. This is exactly the reasoning that Meyer uses in "Signature in the Cell". He looks at the complex inner workings of the cell to argue that it could not have arisen naturally.
As an explanation for the non-scientist or lay reader, of the amazing DNA/RNA/protein machine inside the cell it is a well-written and easily understandable treatise, although he does belabour the point a bit.
However, to really understand this book, you have to understand where Meyer is coming from. He is one of the directors of the "Discovery Institute", a right wing, political/religious think-tank, so his book cannot be considered as a work of science but rather as propaganda. As with all propaganda, it is a skilful blend of truth, half-truth and downright deceit.
His basic premise is that in order, to function and so be classed as "alive" the cell must have in place, a complex interdependent system of DNA, RNA, ribosomes and enzymes and that since all these parts are interdependent this could not have arisen by "chance". Of course, what he does not say is that no scientist working in this field is claiming that this is what happened.
While he denigrates the work of scientists working on "origin of life" scenarios, such as 2009 Nobel Prize winner, Jack Szostak, he does not at any time explain how the designer went about creating life. Instead he uses a form of abductive reasoning:
X is necessary to the occurrence of Y;
Y exists;
therefore X must have existed.
Applying this to the cell, Meyer argues that the only way the information in DNA (Y) could have come about, is if it had been designed by a conscious intelligence (X). He admits himself that this argument will break down if it can be shown that there is any other way that this information can get into DNA. If it can be shown that this "information" can be built up slowly, bit-by-bit, then ID is invalidated. This is exactly what origin of life researchers are in the process of doing.
In conclusion, read this book if you want to understand how the cell works but be suspicious of his central tenet, that the cell was designed by a conscious intelligence.