Bugs
Screen stops turning orientation, even in settings menu G-sensor no longer moves. - POSSIBLE FIX : Go to taskmanager and kill all tasks - All credit and thanks go to casca
Calendar widget crashes if more then 20 appointments - TIP : Just remove the widget since it will keep crashing until you remove it...
Other HTC widgets seem to be causing lag too.
GPU Rendering can't be forced.
Live wallpaper stops on switching between screens
GPS issues - Possible fix : Download gps status on the market and clear the a-gps data - if this works all credit and thanks go to matmar
Screen starts "jumping"
When browsing/camera/other Sense 4.0 related tasks -> It looks like there is "noise" on the screen. Like this
SIM card stops working/restarts/no connection
The three dot menu button appears in some ICS native apps, like the YouTube app for example. - Fix for this in Dev section (requires unlock)
Tegra 3 games (and some others) lag, this is probably connect to some video driver bug. (Hardware is fast enouf to play it without lag)
Screen reactivating after using the lock-button (only 1 click ofc)
When opening the Clock app (just by pressing the clock on your homescreen), and moving to the Timer-tab (the one on the far right) it always adds one hour, one minute and one second to whatever time you set it to.
Issues
Lag in Multi-Tasking window and other elements - TIP : Go to Dev Settings - disable animations. This improved the speed a lot for me (even thou most animations keep on running, only the excessive ones get turned off) [This lag is clearly a software issue, other launchers are lag-free; should be fixed soon]
A lot of people are reporting signal problems. (No clue what's causing it)
Yellow spots on the screen
Always try to Factory Reset your device if you have a problem. Most of the time this fixes it. (Last resort)
Post your bugs and issues and if they get posted frequently I'll add them to the list.
Note to people who are planning on buying an HTC One X :
The device is still a great piece of technology, every software has bugs in it at the start! Don't get dissapointed because there are some minor glitches in the software, most of them will be fixed within 7 days from now (Update).