I've experienced no unusual behavior (no hangs, no missing menu).

Using with an Onkyo RZ900 (latest firmware) receiver, and running the Jan 19th OPPO 203 firmware (latest version), I've lost the system menu once (requiring a reboot) after stopping a Blu-ray, and the only UHD disc I played (XMen Apocalypse) froze half way through, also requiring a reboot of the player.

My Samsung UHD player has never frozen or lost the system menu