I'm sad to say that this course will be of no use to those wanting to learn Slovene. The aim of this review is to illustrate its shortcomings and suggest improvements that could be made.
Problem 1 - no accents
This problem alone is enough to render the book almost useless. In Slovene, any syllable of a word may be stressed. Get it wrong and you may end up saying a completely different word. This is especially evident in the case of the letter 'e', representing different sounds in Slovene. Apart from being stressed or unstressed, it can be an open e or a closed e. It might also be a schwa sound, the sound found in words such as English 'the'. In other words, how will you pronounce the common word 'vecer' (evening)? There are eight(!) options available... And what about the word 'svet'? Is it the Slovene word for 'holy' or for 'advice'? Almost all courses and books on Slovene make use of accents to indicate the pronunciation, since it is impossible to predict. The only two exceptions are this book and Teach Yourself Slovene by the same author. I never thought I'd say a language course in which you will have to guess the pronunciation of each and every word.
Problem 2 - Very limited vocabulary
The reviewer Gwilym mentioned how very limited the vocabulary of this course is compared to Colloquial Czech. The same goes for almost all the Colloquial courses on Slavic languages. Colloquial Czech, Colloquial Ukrainian, Colloquial Bulgarian, Colloquial Slovak, Colloquial Russian are all excellent courses with a well-suited vocabulary. Colloquial Serbian is decent enough. Only Colloquial Polish and Colloquial Croatian are a bit off the mark and then Colloquial Slovene that cannot even be compared to the other courses.
So only 1 star to this course, that star is for a decent (but not great) explanation of the grammar. Two stars off for the very limited vocabulary and two more for the lack of accents.
I'm glad that Routledge offers many excellent courses in Slavic languages and I can only hope that they will one day publish a Slovene course worhty of their reputation.