I think there's a lot of factors at work, the search is terrible but there's plenty of app recommendation services now, one of the big issues seems to be that there's now a mindset of "£1.79? That's really pricy" and they'll move on pretty quickly. That's a big barrier and it's not going away anytime soon really, but alternatives like IAP are now getting push back and mobile advertising doesn't seem to be a solid cash stream yet.