As for specialites, I am fine with the idea that they can do more than just what their names imply, but I am still in the boat that if they have a specific theme name, than others should likewise exist, such as scout (not a Weapon Specialist who spends his or her XP differently) or Officer (which, IMHO is vastly different than a sergeant).
As I said earlier, I havent read all the rules yet (saving a good deal of it for my flight to Germany tonight) but skimmed it enough to get some early impressions.
To me a officer has the big interaction talents and knowledge/lore skills while a sergeant has actual battlefield skills and talents. One has Air of Authority, the other has Double Team and so forth.
I would like to see the following specialites. Grunt (standard guardsman), Officer and Scout.
I think Storm Trooper should be +5 BS not Toughness.
Commissar should have a willpower bonus as well.
There should be a second way to get an aptitude for Willpower other than Psker.
I would rather have the characters built around 3 tiers of characteristics (easy, average, hard) that they get to pick, 3 of each as they wish. Easy is 100/250/500/750, average is 250/500/750/1000, hard is 500/750/1000/1500 or something like that, with skills directly linked to that. So if you have STR as easy, STR skills are likewise easy. I find that would be similar to how it is now, but less involved.
Talents would take a little more work, I dont mind the tiers they currently have but they should also be associated with a characteristic.
The talents and skills listed by the specialty would all be 100 or 200 point purchases, no matter your aptitudes.
Wounds should be based on regiment/homeworld, not specialty, and Fate should also be based on regiment/homeworld.
Not sure how I feel about regiment characteristic modifiers of +3/-3 degrees, +5/-5 seems more impactful, but barely so I dont see why they made it +3/-3. I suppose because if you doubel up form different sources, before you know it you are at +10 STR and so forth, instead of +6.
I do not expect any of my suggestions to make the final cut, as I am sure most people enjoy the game as is, but these are some of my early reactions. Just trying to share.
Most likely, I will just adapt these specialties as alternate ranks for Dark Heresy Guardsmen.