Mine arrived and so far very impressed with the speed.

One surprise: back and recent buttons are reversed for standard, and like Samsungs were (back is on the right). If you want to switch to back being on the left, search for "Mirror buttons" in settings. It's under Full Screen Display for some reason.

They have it in the Mi Store now with the price of $899:

https://www.mi-store.co.nz/product/MZB7259EU/Mi-9

I got a variant today, the Xiaomi 9T 128GB (non-pro). I've been playing a little. Hardware is very fast, and it feels like a nice phone. The in-screen fingerprint reader is variable - sometimes really fast, sometimes takes a few seconds. MIUI 11 so far seems ok, I have all the Google apps and things seem to work fine.

Update a few hours later - still quite impressed. MIUI works just fine, and hasn't caused any problems at all so far - early days. All apps seem to work no issues. Phone is nice and fast. Some settings are in somewhat weird places but I think that's partly due to Android 10. I'm thinking somewhat positively about MIUI.