Pros
Activision has some very well-known titles, which can be good or bad. Sequel-itis guarantees you know there's a job waiting for you next year. I haven't seen many layoffs. Decent studio autonomy and royalty structure mean every developer is different and there's not a lot of mother ship influence. Compensation is fair.
Cons
The schedules are aggressive. Putting out a game every year has turned into closer to a seven-month development cycle, but in the right studio you won't work weekends. Way too many producers where I am, and more than half are frustrated art directors and game designers. There are too many cooks in general and it slows and confuses things. Weak tool development, and overly tight purse strings in some surprising areas like office equipment.