So I recently picked up the first Gaunt's Ghosts omnibus, currently part way through the first novel and... woah.

Very different in tone and general depiction of the IG compared to the nearly happy-go-lucky view in the Cain books (I say nearly, but there are traces of 40K Grimdark, mentioned in a casual off hand manner).

The IG as depicted by Abnett reminds me very much of turn of the Napoleonic era military politics, especially with the jockeying of position and regimental rivalry descending into near guerilla warfare at times. This isn't even getting started on the 40K specific elements such as inquisitors or Chaos taint.

No wonder the Imperial Bureaucracy takes so long to mobilise IG forces - they're too busy backstabbing each other.

I would have thought that with the more tangible nature of the Emperor would have helped focus the Imperium into combating its enemies, but I guess that's going against the theme of the setting.