* phone calls app gets unresponsive (very rarely, but happens)
* main camera sometimes (~50%) doesn't turn on (have to switch to front and back again)
* GPS is slow and unreliable
* the sd card only mounts every 2nd time booting the phone since 4.0
* it's the only device on my network, which doesn't get a new IP address on my home network after some time in standby.
* bluetooth in my car (Renault) is a true PITA. On X at least the phone connection was reliable.

...to be continued...

EDIT:

* new camera pics sometimes don't show up (or are append to the end)

EDIT 2:
* sometimes after reboot, the touchscreen becomes unresponsive. so i can't unlock the encrypted container (home)
* in aliendalvik I often can't move the cursor (correcting text). In fact the cursor is movable, but jumps back to previous position on typing.