I really wasnt impressed by the 4 videos released so far. It looks exactly like a spiced up StarCraft and judging from the gameplay videos there is nothing new to it.
Howver, it seems that Space Marines wear a crisis shield now, so i guess SC2 will probably have a lot more micro and most units will have at least one ability. I guess Marines will have drugs and their shields.
Anyways, the only thing i was REALLY impressed about where those 4 legged protoss walkers who are able to walk over cliffs, and, on a slightly different note those jumpengine-driven beserker-marines, however i think their ability must be activated, while the protoss-walker work without a manual ability.
Then again, i guess we will see something along those lines soon enough in Supreme Commander as well, hence why we have real physics.
All in all, i can say im rather dissapointed from what i ve seen. I have played StarCraft for like 5 years, sneaking up to the computer in the middle of night when my parents were sleeping btw.
Judging from Blizzards comments SC2 will be much like SC1, from Interface to eco and counter-system. It seems to be really just a spiced up version meant for korea (

) with a LOT of micro and skill-based gameplay added.