I finished the campaign last night. It's generally pretty interesting, although I would have liked to see more limited force missions instead of the typical base building ones. The ending is very abrupt though and things end on a big cliffhanger, just like the C&C3 Nod campaign. 😛 There is also a separate singleplayer mode called Global Conquest, where you play a turn-based game in moving armies and building bases around a world map, and fight the individual battles in real time.
I have not played it online yet and don't know how the new stuff affects balance. My impression was that the Black Hand faction is a bit underpowered though. There are also some known bugs, like the fact that the Titans can crush each other. They will probably need some patches to get the balance right, as they did with C&C3.