That's good to hear. When it paired, did it show up as "Device" or was the SmartThings device handler automatically chosen as the device driver?
I have posted a v0.1 beta device driver for the Xiaomi "Original" Temp/Humidity sensor on GitHub. EDIT: now updated to v0.5, fully functional and compatible with both of Xiaomi's models of Temperature/Humidity sensors - please see this new thread for Xiaomi device driver releases.
It is reading the reported temperature and humidity values correctly so far, but I missed the first battery report after pairing, so I still need to change the code for that to work.
I did see the one Temp/Humidity sensor I was testing remain connected and reporting to the Hubitat for over an hour, but it dropped the connection after about 90 minutes. I was able to get it reconnected by going into "Discover Devices" mode, and then short-pressing the sensor's reset button, waiting for one long blink (failed to connect) or three-quick-flashes (successful connection), after each press.
On the third press, I saw 3 quick flashes, and it was reconnected without having to do the full pairing process! That's somewhat good news.