You will be expected to operate at 100 mph, every single day - that often includes weekends. Work/life balance is not prioritized. This is a very "yes-man" environment, so while upper management may sometimes hear you out, you will only rise to the top or get promoted if you avoid even politely challenging a demand or an idea.
The top executives are secretive and closed-minded. You'll hear major company news breaking as soon as the press does. Promotions or raises are very, very rare. Minimum of 5-6 years before that's even a consideration. Raises are extremely small, and bonuses are also nothing to write home about (if you qualify for a bonus, which most positions do not). This is a "lifetime" job environment, so expect to hunker down if you're looking to climb.