Pros
10-15 years ago CSC was a great place to work. There are still many good people there. So long as you're doing billable work you're probably safe from the annual retrenchment rounds. Good online education/training resources (though you have to use them in your own time). If you make the effort you can establish relationships with motivated international colleagues some of whom are fabulous people.
Cons
Too many to relate really - see many of the other negative reviews here since all the ones I've read seem accurate enough. Culture is rule-bound but the rules/procedures aren't useful or helpful. No pay rises for 4-5 years. Brain-dead/mean travel expense policy. Work styles and team management structures hopelessly out of date (waterfall IN, agile OUT (though lip-service paid to the name). Terrible client contracts written and teams have to dig CSC out of the situation so created and take the blame for failing to meet financial targets. Any innovation has to come from individuals on their own time, no support given to allow things to be run with. On and on I could go... Its decline as an employer of choice and as a valued partner to customers has been a gradual one but inexorable.