Few Egoistic, Short-tempered managers (esp in NFGW/Firewall/Security BU) can make your life hell (This may happen in any company, but mentioning it as I have seen/experienced it here)
w.r.t above point, have seen many of team members under such managers, go through serious stress-related health issues up to the point of getting admitted to hospitals, meditation centers, or starting counseling sessions for depression.
Internal changes are possible but have to go through the lengthy process of bureaucracy.
Grade change/promotions take a very long time.
Hikes are not aggressive and if you are staying long, pay would be drastically less than compared to your peers outside.