Took me 10am to 2pm to update to 8.1 on my htc 8x here in the Philippines. My phone is unlocked. I love the new features but just like everyone else, I don't like what happened to the hubs. I have no random reboots. No power button problems. No problem with the cursor. Love Cortana. Here's some problems I have encountered:
1. Some text messages were messed up on my second day. I didn't know how it happened. Of all the messages, it was my wife's thread that has been messed up. The call history was ok but the message thread seemed to be tied up to a hotline number of a restaurant that's not even a cellphone number! All her prior messages are now under that restaurant hotline. But when I open the profile of the restaurant, no threads are there but under messages, it was all there. Is someone here experienced this?
2. I love the calendar but intermittently, when I long press the back button and fire up the task switcher, I can see the calendar open even if I didn't open it. Some memory handling problems?
3. Battery problems. Seemed to drain faster than before.
4. After the update to 8.1 and the update to Angry Birds star wars II, playing it requires me to be online. But not after the second time I ran it. Not a big deal.
Since there's no turning back, I will live with this. It's a developer preview anyway. I will post updates when I encounter more.
HTC Specific:
I stopped using the HTC hub until an update is available. The live tile is not updating every minute anymore unlike in 8.0. The clock is late a few minutes than the real system time. I also saw this in HTC threads where screenshots were provided. Clock is late. To get over this, install the clock hub from the store and a weather app with current location, if you need such things.