My biggest gripe :

Calendar events alarms :
We can't set an alarm with a precision of 1 minute, only 5 minutes (ie : 7h16, 18h43, etc... only 7h15, 18h45, etc...).
On my old phone I had three consecutive alarms to wake me up, each one set to 1 minute after the other.
Other reasons can be found to need accurate alarms.

That is something I really look forward to in the next firmware release.