I use it for a couple subscriptions, most of all Marco Arment's The Magazine (best magazine around for tech-minded people btw).
I haven't subscribed to a lot of things, mainly out of principle. I want the iOS only version, not paper + iOS, but I find that most publications charge you exactly the same amount for iOS only subscription as they do for paper + iOS subscription. That's just not acceptable, ripping people off like that. So I only subscribe to magazines that offer a discount for iOS subscriptions, to counter the substantial less operating costs of not providing printing, paper + delivery.