Pros
People are generally really friendly. There are still some good engineers around, although I've seen a lot of good engineers leave over the last few years due to many of the reasons highlighted below. Work is generally not too stressful - this will depend on your project but generally speaking people don't have to work late into the evening etc. There are some interesting projects around and you get the opportunity to work with big enterprise clients. The benefits are reasonably good. You get a lot of flexibiltiy - depending on your project, you can come into the office as much or as little as you want.
Cons
Progression is generally slow and it's not a meritocracy - I've seen plenty of people get promoted who don't deservice it and many people who do deserve it, not get it. The biannual performance review process which decides promotions/bonuses is really painful, arduous and gernally speaking doesn't make any difference. A 13% pay rise when you get promoted is poor. I was very lucky to get 20% a couple of years ago but they have since reduced it to 13%, which makes the slog to get there much less appealing. Generally pay is below market rate. You won't be rewarded here for being a good engineer. I am biased, but IMO, alongside the people winning work, the good engineers are the companies most valuable asset, yet Accenture make no effort to keep them happy. Graduate/Apprentice hiring now significantly over-indexes on positive descrimination.