The game itself is great but it won't run as smooth as you'd hope due to poor design and technical difficulties.
Now about the factions. The game consists of three different divisions, Novus, Hierarchy, and Masari. Novus has this feature where it allows you to create invisible network towers that allow rapid deployment of troops anywhere onto the battlefield. I have never seen this before in an RTS, really innovative idea. The Hierarchy are exactly the opposite of the Novus, unlike Novus who focuses on speed, the Hierarchy has a number of huge units entitled "Walkers". These giant powerhouses are slow but strong. However, it comes back to rape you later on because of the crappy camera you can see about only 2-3 walkers on your screen at a time and thats a huge nuisance. The Masari isolates itself from the other two even further with a "light/dark system" and other new ideas that may or may not be confusing.
Finally the storyline. I'd say 10/10. Sure, Earth falling under alien domination and another alien faction hidden under Earth's oceans isn't totally believable but the manner in which it is presented is enjoyable. I found myself completing the mission just to see what development occurs next in the storyline. If I'm doing this then the game has a really nice storyline.