Being essentially a "WH40K Roleplay", Dark Heresy is heavily inspired by all manner of cannon creatures - xenos, daemons, sorcerers and so on. It seems the most logical move - if we make a game about WH40K, there should be WH40K stuff in it. On the same side, we have lots of new xenos, the whole upcoming Creatures Anathema are not about eldar, okr ana tyranids only. It goes not only with xenos, but all other manner of thing. Even the Calixis Sector is brand new for DH. That is also quite easy to explain - making a game in a setting so huge and (at times) controversial in sourcebooks, it's better to start anew, especially if the game is played not only by Warhammer 40K fans, but by players new to the setting, who haven't read all that codi and fiction, don't have a 3000 point worth army in the closet and so on.
So, there is a mix of "good old things" like daemons, eldar, nurglings and the like, and new ones. Keeping in mind that the best is always in the middle, and extremes tend to get... well... extreme, I want to ask - what do you prefer? The old canon stuff or the new one?