Pros
You'll be hard-pressed to find a work environment more exciting. There's always something happening on the Hollywood lot. Overall, people are laid back and friendly and less corporate than some other studios. You're likely to get many more days off then you would at other companies. For instance, we've been getting three extra paid days in the summer as well as over a week of paid time off around the Christmas/New Year holidays.
Cons
As others have mentioned, you do pay a prestige tax. Compensation is lacking compared to comparable positions at other companies. Jobs and promotions often result as favors to friends and friends of friends rather than loyalty and merit. And while most people are friendly, prepare to encounter a lot of superficiality. You looks, or lack there-of, may hinder you career there. Not really a place to try and transition from the business to the creative side. Paramount also seems to over-hire sometimes and you'll be stressing at the end of the fiscal year, hoping you're not part of the resulting mass layoff. HR is essentially useless, which should come as no surprise. The lot has become more of a rental facility than the movie factory it was during Hollywood's heyday. Lot's of TV productions happening. Very few films. There have been rumblings that Viacom will be putting the studio up for bid before too long.