Having used Blackberry 10 OS and also WebOS I see a lot of similarity to the swipe version of iOS on the iPhone X, the swipe up to open or go to home screen and the half swipe up to the app switcher from both the above, the swipe along the bottom between apps reminiscent of the Playbook OS, along with a tap to wake from the Android world. I find its use much more intuitive than previous iPhones.
I thought I would miss the fingerprint reader, but face unlock only seems to fail when laying flat on the table but is unlocked as soon as the phone is picked up. It even works in the car cradle I have set lower and to my left as long as I glance down, important as I need to be able to switch between music or audiobooks and calls (I have Do Not Disturb whilst driving turned off or it would interfere with my work.)
I haven't had a chance to use the camera in anger yet though what I have taken does not disappoint.
Other than that it performs as I would expect for email, messaging and contactless payments as previous iPhones have, though I tend to use the watch for payments rather than the phone.
I'll keep this fairly brief for a first impressions post so leave it here.