Having a windows phone for a while now, I can tell you this sort of thing was really unnerving at first. All I can say is that you get used to it.

Questions like: "is that a label or button?" were frequent in my mind because many "buttons" that are just text, with nothing to suggest they're clickable.

However, once you mind is free of the notion that a button must have a border around it or be underlined, you start to admire the simplicity.