it's not out of place really, there's many apps with many different designs, so it's fine. also not all apple's stock apps are white symbols on a coloured background, like notes, safari, camera, photos, weather, contacts, compass, youtube, maps, remote & findmyiphone (ok not a stock app, but still an apple app). the ones that are as you described are phone, messages and email, so actually FEW stock apps are white symbols on a coloured background.....
Phone, Messages, Email, iTunes, Voice memos, Stocks, App Store, iBooks, and iPod technically since it's still around, so yeah, not most but just under half. I still maintain that it looks like the odd-one-out. You like it though, good for you. I don't.