I just bought this yesterday. IRIS Scanner is Ok but certainly requires some effort to get this unlocked. Overall performance is not great, not sure if this is something to do with OS or Apps. Most the apps are not syncing ( SplashID is crashing) not sure if they are optimized for Windows 10 Mobile.
It is cheap plastic and very light, I like the battery replacement idea and Dual SIM.I somehow feel that my earlier Nokia Lumia 920 felt extremely premium for the price Lumia 950XL demanding.
Not sure where Microsoft is heading.