I found this book fantastic. On visiting Slovakia, I found this book extremely useful. My only criticisim of it is that a very few words are not exactly accurate, & as it is written in the USA, it sometimes seems geared towards an American audience when explaining something about the country. The content matter is perfect, it has a dictionary from English to Slovak & visa-versa at the back, & at the beginning explains clearly & easily how certain letters should be said. I've now been studying Slovak for 2 months having bought this book previously, & I still find it useful.
It is very hard to get any Slovak books in the UK, but trust me, this one is the one you want to buy, it far excels the lonely planet central european phrasebooks Slovak chapter & is small enough to carry around without you noticing. If you are on of the many traveling to High Tatras in Western Slovakia to ski, you will need a phrasebook at some point... make sure its this one!!