Occasionally updates are delayed until you shutdown and reboot. Memory is serialized to disk and then reloaded at start up - if the physical state of the pic changes (you undock or unplug, close the lid, even move to another network) you may have trouble restoring and be forced to reboot anyway.
This could result in data loss of whatever you were working on, but I've never really had that.
I don't think there is anything hardware/os-wise that could be bad for your pc by hibernating.