First of all, I think I’ve already mentioned here that I adore Insomniac. They’re just cool dudes. But second of all, this is actually a good, concise critique of the majority of facebook games (and whatever mobile games there are that take after them). I don’t really have much to say that isn’t already mentioned there, so go check it out.
On the subject of how problems and goals work in game design, here’s an Extra Credits episode more relevant to “core games” on choice and conflict. It’s not a new episode, but I thought of it right away as I was reading the Insomniac post, and I don’t think anyone has actually started watching Extra Credits on my recommendation yet. So I’ll keep linking to good episodes and that’ll be enough.