The non-stop attrition: When all of the teams merged together to create the "new" Doom team 2 years ago, there was around 140+ developers to make the game. Now, there is only around 50. The non-stop attrition has gotten so bad, that they had to contract outside the company for the multiplayer portion of the game, and we have contractors doing a bulk of our art work.
The non-stop reboots and changes of direction: Every 4 months or so, they tell us that the current direction is all wrong for doom, and will re-boot most, if not all, of the game. This means that for over 2 years of work, there is no game to show, beyond 1 or 2 blockout levels and numerous prototypes.