For any Space Marine / Tyranid / Battlefleet Gothic lover, I suggest you read it and all his other books for that matter, anyway, please take a look at my review below and go read it.
They stop off on the way to seek aide in the coming war from a successor chapter the Mortifactors, but they are shocked by how much they have deviated from the Codex with their barbaric rituals. None the less aide is given and they head out to Taris.
The book follows several other characters from different view points and really builds up to the events that happen. Mcneill always manages to give great detail about the surroundings and events making you feel your actually there.
The Space battles are fantastic with some real epic conflicts, from the mightiest star ship to the small fighter craft, the book also describes the Tyranids ships in great detail describing the devourer in all its glory. One particular part of the novel involving a gigantic space borne refinery is a fantastic read so I wont spoil it here.
The lowly scum of the planet also get involved with their own little battles and produce some surprising villains and heroes, I love reading these parts as it embodies the Imperial life very well. Personally this is where I would probably be if I were alive in that time, scum of the hive lol.
Inquisitor Kryptman from the Ordo Xenos and his team of Deathwatch are heavily involved and Ventris leads them a couple of times into battle. Most notably into the heart of a Tyranid Hive ship. This is where Uriel starts venturing away from the teachings of the Codex, which is an essential part of the Ultramarines omnibus and Pasanius follows leaving the very much annoyed Learchus to head the Ground battle.
The book really portrays the Tyranids well, from the first strike to the never ending tide of small aliens, right up to the lumbering monsters. Death and carnage are everywhere and it leads to some very good reading. Some very inspiring heroics come from the strangest of places and the Mortifactors fight well with the Ultramarines, even though they are very separated from the Codex.
In the end they prevail, but not without great losses including several planets. Once a world is touched by Tyranids, it is never the same. Another great part of this book is that it involves the Death Korps of Krieg which I am sure will please some readers.
You're comments and thoughts on the book if you have read it, are most welcome.