I see it like a good boardgame, one that I don't play very often but look back fondly on, and feel the desire to get out every now and then.
If you've only played the demo, you've only played 1 v 1. The game becomes exponentially more interesting with a full group of 6, especially, I think, if you're all strangers, and don't know what to expect of the other players vis a vis backstabbing.
My favourite game mode was Diplomacy, in which all players start on the same team (with shared radar) but -being a nuclear war game after all- this truce is always short lived, and factions will form. I like that the game doesn't feature any "diplomacy" stats to manage, it's all on you and your chat with other players to make and break strategic alliances.
Some people don't like its simplicity, but this is really a draw for me. The fact that you all start with the same units (and never build more) means that the strategy is all a matter of what you do with what you have, not who can manage tech trees and build queues the best.
It's what, 10 bucks now? Definitely worth checking out.