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.