Just wanted to add you cannot rampage around with a large group of marines or even all your squads and terrorize anymore. You will be cut down to pieces if you do not utilize all of your abilities and the cover. Frag grenades in the game are much more powerful too. A single nade can decimate an entire squad. So when you see one being tossed your way.. its a good idea to drop what youre doing and run for it
I'm just really surprised how useful the squad-specific abilities are now. Most of the time the difference between retreating or swarming your enemy is a well placed grenade to blow up enemy cover, or a well-timed ability. Even the scouts now are extremely useful. The enemy likes to garrison a lot of buildings with heavy bolters and the scouts can easily topple a building with a thrown satchel charge. But the enemy can do the same to you

and they do it often. Half the time i dont even notice a nade they threw at me until one of my squads goes flying through the air in pieces.
It also feels very RPG-ish in the amount of wargear you get all the time. The amount you find depends on how many objectives you complete and how many enemies you kill. Every single squad can be fully outfitted with different weapons/armor/accessories. For example, you can turn your force commander into a ranged unit with a heavy bolter or equip the chainsword/pistol for melee.
At least in the first few missions, your force commander is not nearly as powerful as all previous games. But he is still extremely useful on taking on single squads himself. If you send him in against 2 or more squads by himself.. he's going to be shot down right quick without backup. But with proper covering fire he can really tear it up.
Oh, and just about everything i've seen so far blows up

its really neat. Its like CoH but taken to the next level. Game is beautiful

I just hope the SP campaign lasts quite a while and will have some good replay value.