Apple has installed a permanent undeletable Apple Watch advertisement on your iPhone
The most notable feature of iOS 8.2 is the Apple Watch application, which offers a few promotional videos for Apple's first-generation smartwatch, as well as a link to the company's website to "learn more." Soon, that application will showcase all of the Apple Watch applications you can download, but for now, it's just an empty screen.
If you don't want the Watch app to be stuck on your phone forever, just don't update to iOS 8.2.
Otherwise, it will join the legion of Apple-made apps you can't delete from your iPhone, including Passbook, Tips, Stocks, Weather, Calendar, Clock, FaceTime, Contacts, iBooks, Compass, Maps, Health, Newsstand, Photos, Camera, Notes, Messages, Voice Memos, the iTunes Store, and the App Store.