Do you like skirmishing against computer players in RTSes, but don't think they simulate humans enough? Great, you'll like AI War. It's asymmetric, about halfway between skirmish and campaign modes, and it doesn't try to act like a real human.
Do you like really long RTS matches, but don't like that they usually turn one-sided after the first half an hour? Great, you'll like AI War, it stays tense and balanced for the entire 5-20 hour struggle.
Do you like HARD games? Play AI War. The difficulty levels you can select start low but go up to truly legendary heights.
Do you like constant battle? AI War may not be for you. Yes it's real-time, but you will spend a fair amount of time thinking and plotting and planning. Anxiously.
Do you like games that you can finish in one sitting? Don't play AI War. Just don't.
Do you like an easy, relaxed gameplay experience? Probably don't play AI War. You can set the difficulty low, but it's boring...and the difficulty goes up as time goes on, not down. Unless you're playing way below your skill level, the endgame is always a brutal nailbiter and if you are careless you can get wiped out. AI War needs you to think about what you're doing for the whole game.
This game is not for everyone, and it takes a big time commitment. If you're sitting on the fence, I'd recommend avoiding it. There is no "let's sit down for half an hour and see how it is", it will take a lot of time no matter what. Also, you will absolutely want to sit down and play the tutorial, even though it takes a couple hours. It's basically just a short version of a full game that walks you through the unique strategies of AI War with kid gloves on. Playing this game like it was any other RTS is the biggest mistake you can possibly make.
As for what makes the strategy different? You have to pick your battles. The AI is generally not that aggressive, at least not in a planet-by-planet way, but every single time you expand it's like kicking a hornet's nest. Discretion is the better part of valor, and not just because you risk your current armies: In this setting, your opponent is much bigger than you, but it also has other interests much bigger than you. If you stay small and pick your targets carefully, you can keep from drawing too much ire, but if you try to take over the whole galaxy then your enemy will say "oh maybe these humans are a real threat" and stomp the hell out of you. Don't do that.
All in all, it's a truly unique entry in the RTS genre. If the above caveats don't scare you away, give it a shot. It might not be your favorite game, but it's a truly memorable one, and worth the time commitment to play a few games.