Pros
Company is overall good to employees, however it is a big company and as such, do not expect much personal treatment. The key is to get in to a good group/department run by a solid leader and there are a lot of resources that can be made available to you to help your career. Most coworkers are solid performers and there tends to be some room for advancement.
Cons
Comcast culture is permeating further into NBCUniversal. This was inevitable after the GE buy, but in my limited experience with it, I have not been impressed by what I have seen. Moreover, as they are coming in as the buyer, Comcast people don't seem to be as interested in hearing what experienced people have to offer in terms of operating a large network. Yes, Comcast had some channels on their own, but...let's be real in terms of their scale and reach. Vivendi and later, GE came in with much different approaches that I feel made the transition to "their way" much smoother.