I finished the 4th Apt book Salute the Dark by A. Tchaikovsky and it was all that i expected and more; though the series is supposed to go 10 and there are at least 2 more books in the 6 month interval pipeline, this book nicely rounds a lot of the main plots threads and concludes to some extent the story started in Empire and Gold;
The title is apt (so to speak) since this book is very dark - I saw some complaints how given all the war and violence in the first 3 volumes, most main characters escape; well, up to here since this book is merciless on them; I would not want to spoil some of the most powerful moments of the book but there are so many including personal combat, cavalry charges, mystic foretelling of the future, escape from crucifixions in the nick of time, weapons of mass destruction, land battles, air battles, intrigue and assassinations or tentative of such, but the prize goes to the gladiatorial combats and especially to the climactic one that has all the intensity of the best from Spartacus on...
Since the first part of the series sort of ends here, I really have no idea what will happen next so the fifth book due this summer jumped a notch on my asap list; Salute the Dark is an A+/A++ depending on rereads; if book 5 matches the intensity of book 4 and brings more twists and turns - here there some unexpected ones but mostly the sheer carnage of the war including withing the ranks of the main characters was the biggest surprise - they could jump to the top of my fantasy list for 2010
For "series completists" books 1-4 can be said to form sort of a complete series so go read them...