The most pressing need for this book might be in the semiconductor and optoelectronics fields. As linewidths keep decreasing for transistors on chips, and as clock speeds keep being pushed up, the accuracy of electromagnetic simulations is vital. This gives circuit simulations that can be relied upon, without having to continually write new circuits to silicon [or GaAs].

The book goes into the myriad ways that Maxwell's Equations can be numerically solved. Finite element/meshes take up a large portion of the text, naturally. Also, there is a good discussion of gate simulation. A gate is the key component of a transistor, so its interaction with the source and drain needs accurate modelling. Related to this is a discussion of modelling the capacitances of various circuit elements.

Some portions of the text are more esoteric. Like the modelling of superconductive effects (Cooper pairs etc) or of phonons. While these will certainly be of interest to some readers, most will be interested in the standard circuit simulations.