I've been using Face ID for the past few days, too, on my X, and it's definitely an improvement over the S8's facial unlock (I don't really use IRIS). It's still slower than when I use my FPS on the S8, but if we're talking strictly about face unlock, the X certainly beats the S8.
It isn't the leapfrog technology I thought it would be, but it's still a fairly seamless and smooth experience, albeit slower than Touch ID/FPS in general (the Pixel 2, which I've also been testing, has hands-down the fastest FPS sensor). Face ID can only get better from here on out, too.
With regards to the design, I still have qualms with it. Despite working around it, the notch is still a poor design decision. One, that I think, was meant to make the iPhone more recognizable and iconic than for actual practical purposes. You lose more than you think -- for example, there is no longer a battery percentage in the status area anymore. There's simply no room for it. The notch is what it is; you get used to it simply because you have no choice.
Also, I don't think this is Apple's best quality design. There is a noticeable break between the metal frame and the back-glass panel. Run your fingers between it and you'll feel it. And that camera hump is atrocious, not just in looks either. Putting the X down on a flat surface results in serious wobbling, like nothing I've ever experienced in a smartphone before.
Having said all that, the X is still an enjoyable iOS experience. One that is far superior than previous generations. I like the direction Apple is going. Hardware always mattered. It's great Apple is back in the game.
Now for iOS...