Pros
Some really nice people! If you're lucky (and, ideally, a graduate), you'll get placed in a functional team and get good experience for a while. Competitive benefits package (10% profit share bonus, free lunch, contributory pension, health care). Relaxed atmosphere and mostly nice environment. Flexible working times. Good facilities in the building (nice cafe, showers, quiet areas).
Cons
Limited career progression for Software Developers - can be difficult to get green fields work or to move between teams or try out new stuff. Luck of the draw if you get a line manager who helps you - you may well find yourself pidgeon-holed indefinitely. Very little innovation - majority of work is on legacy codebases - some of which stink. Cliquey with higher than average levels of politics - to be more than just a number, you'll probably need to do at least some politics, which is not everyone's cup of tea! Increasingly high turnover of staff. Senior Management feels out of touch. Steadily heading towards maximising shareholder value as a sole objective - limited values beyond this. Location is drab and lacking in anything to do outside the building if you want a break from the sea of open plan desks - e.g. nearest park 20-30 mins walk, no shops, lots of traffic and roads!