It starts off really well but it loses it's way and meanders a lot. It falls down because GW doesn't want it to end so there are a billion short stories and audiobooks and it's hard to tell what order things are meant to be read in. I still read it because I've started so I'll finish but it's fallen apart because it's being run by a business rather than as a series of books.
Just finished Chronicles of the Unhewn Throne by Brian Stavely. An interesting series, I liked the world and it did some interesting things.
+1 to this. First half dozen books are amazing but around the time it hit Angel Exterminatus it had taken a swan dive off a cliff as it really painfully overdraws out the story for money.
The irony being they could have started the series earlier (leading up to the big campaign where tge emperor annoints Horus) and done some genuinely interesting stuff instead of the tedium they filled it with.