I've played quite a few RTS games, and this has to be the best.
First, the graphics are incredible. I play the PC version on a mac laptop,
because the mac version wasn't out when I got it. So, I have to turn the
settings to about medium. Yet it still looks fantasic.
Second, the story modes are great. The story itself is great, and the fact
that you can play as all three allows you to see the different point of view for
the same mission, which is very exciting. The only bad thing is the Scrin
campaign, which is impossibly difficult.
Finally, the Skirmishes have so many combinations, that it truly promises
hours, and hours of entertainment. You can set the AI to play in 5 different
styles. Also, the AI in this game doesn't give up. You can finish off their
main, and secondary base, but they'll almost always send a MCV to scuttle away
and hide somewhere on the map.
I've not tried online with this game, but LAN with this game is so
much fun.