Pros
Pension and other perks are very competitive (e.g. Aviva Digicare+ app which lets you book online GP appointments. Useful for getting prescriptions for ailments such as depression, stress, brought on by your day to day CGI experience).
Cons
Far too many to list. I have never worked for a company where there are so many people who are either a) incompetent or b) utterly self interested or c) both. If you are a competent software developer and have got used to working for modern, product based companies, as I have, my advice is to not touch CGI and consultancy in general with a five metre barge bole. Don't be fooled by the notion that you can simply get on the internal jobs board and move to another project -there aren't enough on the go if you're a Java developer and if you're experienced your pay grade will disqualify you. Managers are terrible - I've had four in 8 months and I only liked one of those, although she barely spoke to me (probably why I liked her). Management style tends to fall between "don't give a toss about you" to "I'm going to micro manage every aspect of your working day". This even applies to scrum masters on projects who aren't even your manager. CGI is a bureaucratic hell - they actually send you fake phishing emails to "test" you.