Usually travel guides about the two republics tend to concentrate
fully on the Czech Republic (and then mainly Prague), with a chapter
about Slovakia tagged on to the end. You often find yourself wondering
if these guys actually set foot in Slovakia at all, or just wrote
the book from the Czech capital.
Brewer's travel guide, although again heavily weighted in favor
of the Czech Republic, is different. There are three chapters in
the Slovak section of the book, one each for Western, Central and
Eastern. Most of the major towns and attractions in Slovakia are
covered, with the notable exception of Kremnica. There is also some
useful information about Slovakia in the opening chapters of the
book, including a short history of the country and a superb piece
about the differences between Czechs and Slovaks.
Brewer presents a fair account of Slovakia, and mostly gets it
right when recommending hotels and places to eat. If you are going
to visit both republics then this book is a must have. If you are
only going to visit Slovakia, then it is probably still worth your
while getting this travel guide, even though you might end up only
reading a third of it.