Now that we can actually own the book, at least some of us can, there are bits of information coming right from the new Horus Heresy book 1, Betrayal. This is our first glimpse at what is in it. Realize that people that just got the book, have not had much time with it yet. However, from what I have heard, its worth every bit you paid for it.
There will be bits that I am trying to catch up with regarding information that resulted from Games Day UK all day. Next up will be a lot more 'Betrayal' information.
From a Hobbyist with the book (did not want name mentioned)
Got my horus heresy book so here's some select rules you might like to know.
Cataphractii terminator armour is 2+/4++ with slow and purposeful instead of relentless
Primarch standard special rules are:
Independent character, eternal warrior, fear, adamantium will, fleet, fearless, it will not die, master of the legion
Angron is a combat monster
Fulgrim is a finesse combat king
Horus IS strategic genius
Mortarion probably will never die :P
Also, Mortarion has rules which means he can assault a minimum 18"