Adapting anything into a new form of media is always a taxing process. Whether it be video games into films, comics into TV series or even short stories into full blown tales of thousands of words, there's always a high risk of something going wrong. This is unfortunately true with even the closest of media formats with turning text on paper into spoken word stored on a CD.
Let's be clear before this begins: This isn't a review of the trilogy of novels (Horus Rising, False Gods, Galaxy in Flames and the Little Horus short story) and their content so much as an analysis of how well it translated to CD. Specifically focusing upon the quality of voice acting, editing, additional sound effects, music and pacing. The latter point is extremely important as this is a trilogy of abridged novels with scenes cut for time. If you want an opinion of the trio of books: Buy them if you are at all interested in the 31st millennium, they're the best gateway to the series you could ask for in spite of individual flaws.
The first real point to comment upon is the choice of voice actor: Martyn Ellis. Expected to provide voices for more than twenty characters, narration and make each one distinct from one another the Boxset required a person with a broad vocal range. Thankfully Ellis succeeds in this area, giving many characters their own distinct tone for the most part. With the exception of a few such as Abaddon, Jubal and a few others they have distinctive voices which can be picked out immediately as belonging to a specific character.