I'm looking through the top free iPhone apps in Germany and I can't see a clear trend. Also, I'm not sure how to prove or disprove my point - because being a top app is orthogonal to looking like an amateur effort. WhatsApp has long been #1 here, and while I welcome its stock navigation UI for usability reasons, I think their tacked-on timestamps are as "amateur" as their name.
Some of the UIs are badly imitating UIKit, like Zoosk. They still often replicate the navigation concepts, UIKit shadows (skeuomorphism), widget sizes … - I don't think the stock look & feel is dead yet.
By "amateur" I mean that I think the typical app consumer is getting pretty good at spotting stock UI and tends to equate that with a slapdash app, justified or not.