I find it hit and miss. I usually assume the quiz/preferences barely make a difference and it's all pretty random. I actually find I like most of my ipsy stuff and my biggest complaint is usually shade (uh...and all things J Cat or whatever that godawful brand is) and that's pretty much impossible to personalize.
@dusky - where do you review? I admit, I never go to the ipsy site. But I always think I should because I know those who do get really involved sometimes get bonuses and such. But I've glanced at "My Glam Room" and just do not get what I'm actually supposed to do. I'm not going to post pictures of my makeup looks...so what else is there?