3. The notch.
Most iPhone X owners will tell you the "notch" — which houses Apple's TrueDepth camera system — pretty much disappears when you use the phone. "You really don't notice it much," they'll say.
That's just not true. I don't always mind it, but I notice the notch all the time, especially when I play a game that takes up the whole screen, like "Monument Valley 2," or when I turn my phone sideways to watch a video. All videos must crop themselves to fill the iPhone X screen in the first place, but the notch cuts further into whatever you're watching as well. It's not a huge deal, but it's a small nuisance that I hope is fixed in future iPhones. (Luckily you can choose to zoom the video out to remove the cropping, but you lose the fullscreen effect.)
On its website, Apple says "Our vision has always been to create an iPhone that is entirely screen." I, too, look forward to the day when the iPhone is "entirely screen."
2. In general, the iPhone X's camera hardware is let down by its software.
The iPhone X's camera is very good at taking photos and videos, but it's not better than Google's Pixel 2 cameras, which regularly produce better-looking photos on the front and back compared to the iPhone X.
What's notable here is that Google was able to best Apple's smartphone camera with just a single rear lens (the iPhone X has a second telephoto lens for optical zooming; the Pixel 2 does not) and a less sophisticated front-facing camera system, compared to Apple's TrueDepth solution. And so, the iPhone X has incredible camera hardware, but it's let down by mediocre software, which generally makes photos look too warm and inaccurate compared to photos shot with the Pixel 2.
Check out this camera comparison of the Pixel 2 and the iPhone 8 Plus, which has a near-identical camera system to the iPhone X, and you'll see what I mean.
1. I wish the TrueDepth camera system could do more.
Right now, the only real tricks made possible by Apple's TrueDepth camera system are Face ID, Animoji, and a few unique selfie modes in the Camera app.
I will admit Face ID is fantastic, and I love it way more than Touch ID as the primary way to get into my phone and pay for stuff.
But Animoji, while cute at first, is extremely limited, and gets old pretty fast — you can only film 10 seconds of an Animoji at a time, on a plain white background; Apple won't let you add backgrounds or effects or anything fun like that. And the new camera modes designed to take advantage of the iPhone X's improved selfie camera are unimpressive and underwhelming. Apple is starting to wade into Samsung territory with the sheer number of camera modes you'll never use; I'd rather have fewer filters, but have those filters be really polished. In particular, I'm very disappointed with the new Portrait Mode filters, which do not look very good and clearly need some work.
The TrueDepth camera system is one-of-a-kind, but I'd love to see Apple do more with it. Apple made a big deal about augmented reality at its iPhone X event, so it's disappointing Apple hasn't built any clever AR standalone apps that take advantage of the iPhone X's camera yet.