Pros
Your work may impact millions of customers. Opportunities to work on a wide range of software products -- consumer, IT Pro, developer -- and with diverse, intelligent, creative and dedicated people. Great environment for life-long learners, with strong corporate commitment to on-the-job and other types of training.
Cons
Despite many tweaks to the review system over the years, old habits die hard and stack ranking still happens. Stack ranking in small groups (ie under 25 or so) lowers morale and discourages true teamwork. It can pit managers against each other and put them in the awkward position of having to explain a low ranking that's more about politics than performance and impact. It also can make less appealing to work on a high functioning team, since it'll be harder to differentiate yourself and your work.