Pros
The benefits are good and the pay is not terrible. There are a lot of fun and interesting people to work with and the projects I worked on were enjoyable. The work hours weren't bad either. When you leave after a few years, (which I recommend,) having the Viacom brands on your resume will impress future employers. If you're newer to the industry, it's a great place to learn and gain experience.
Cons
There are soooo many incompetent art directors and vice presidents with fancy titles that don't mean anything useful. My team's general policy for dealing with incompetent directors was to add more layers of incompetent directors to do the original incompetent directors' jobs for them while they took long lunches, left early, and scheduled meetings about meetings in which they complained that there are too many meetings and we should set up another meeting to discuss how we can reduce meetings by adding another director. If you felt my usage of the words meeting and director was redundant: good, you've had the Viacom experience. I will leave the finer details of my bosses' shenanigans out of this review, but add that such stories have received the frequent response from friends and family, "How have they not been fired?" The answer: firing someone requires effort. Giving someone a raise also requires effort, so don't expect one. The incompetent directors are also thick as thieves, so if you question any of them, they will defend their dysfunctional hierarchy and outcast you from their high school-style clique, usually by gaslighting you. Don't feel too bad when this happens though, just take it as a sign it's time to take your talents elsewhere.