Aside from most adepts, it's not nearly as useful as everybody claims it to be. Really fast moving objects can't be targeted that well.
Still, what makes it count is the specific powers based on it. Biotic Charge Krogan would be a hell of an antidote to a Brute (though the Brute may still win in terms of sheer endurance, I mean look at Tartarus' Brutes in Halo 2, they're fracking ridiculous).
You should try the first one. It's a damn good game.
I'm more pessimistic towards the second game's plot (but the game overall is still very good) and I hate the third game all round.
Just my opinion. I'd recommend the first one to you.