The atmosphere was casual and pleasant in my office, which was dominated by software engineers and QA folks. I had an excellent mentor, who provided helpful guidance on new projects, which I found to be very important towards promoting intern success. I was even allowed to work remotely for a while after I moved halfway across the U.S.
Cons
Comcast is huge - HR-related issues are much more bureaucratic than at a small company, such as changing system passwords, where you're often put on hold for the helpdesk for extended periods of time, lowering your productivity.