Vantaggi
It's good for career advancement, since it makes other companies' HR managers to think that if you have worked in one of the big four, then you must be reliable, knowledgable and hard working. It's easy to get in in a good economy, especially if you have the right background: BS or MS in accounting/finance/tax because they are always hiring. It's easy to stay in, again in a good economy, because unless you are doing something seriously wrong, they'll keep you. They are offering decent health plans and decent vacation - 21 days, plus holidays. They also offer great training and if you are eager to learn anything, you can do it online - from accounting and IFRS to latest investment trends and tax laws. One could also make friends there because they are very diverse, so if you want a friend who speaks Chinese, Japanese, Hindi, Hungerian, Russian, etc. - that's the place.
Svantaggi
Forget about 9 to 5 job, you'll need to work as long as you have work. Often you won't have weekends too. When you get an offer, divide your compensation by 2, because you'll work double shift. If your manager has a habit of coming to work at 6 am, you'll need to do the same in order to look good. If you don't look good, many people will be happy to point it out to your manager and you have a chance to become an outsider, or just get laid off due to whatever reason they find appropriate at the moment. There is lots of beaurocracy: forms you'll need to fill in, reviews you'll need to write, teleconferences you'll need to sign up for, etc. If you cut all these, most of the time, unnecessary things out, your life will be better in terms of efficiency, but your annual review may suffer because they want you to participate in the social life of the company too. They also force people to volunteer and donate money, and while I am all for volunteering myself, I think people should do it on their own terms. And one's career growth and promotion should not be determined by the amount of money donated for different causes.