Pros
In general: One of the biggest employers in the world sounds like a lot of possibilities and actually a whole variety of terms, as it mostly depends on the project and the client's needs. There is a lot of internal tools and external partners, allowing those willing to learn things to make use of many different sources. In my case: I am lucky enough to be a part of rather small group working for a client from another country. It allowed me, a proactive player, to quickly try myself in other's shoes, i. e. take additional responsibilties. And finally, while getting in wasn't that easy at the time I was trying to, I think that being fired is even harder.
Cons
Apparently, the name is hardly recognized among those without contact with business. It is certainly not a modern more-like-start-up-company, it can be perceived as overly fomalized, since getting some things - even small ones within the company - being done sloooowly. An initial salary for someone starting his career may not be sufficient and payrise period happens only once a year (in December). Probably better watch your activites after work, because the company may be jealous or angry about things being done for someone else.