Pros

Microsoft is challenging. You will be stretched. You will never be bored.
Microsoft offers good pay and excellent benefits.
Microsoft belives in training staff, and you will be able to learn new things and develop.
Microsoft is huge, so there are always a lot of jobs. If you are the kind of person who likes to transfer internally (after you are in your position a year, that is) then you will find ample opportunity.
Microsoft offers an internal mentoring program, which all new employees should take advantage of.
Microsoft supports parents, allowing time off.
Microsoft is about getting your job done, not about face time in the office. If you want to work 10am - 7pm, fine, as long as you deliver. They also have excellent IT which enable you to work from home. There are a lot of people who work remotely or variations of part-time.
Microsoft isn't always an easy place to work, but others will help you. Just ask.
Microsoft dogfoods it's tech on employees so things in tech don't always work perfectly. However, you do have cutting edge stuff, which is really cool.

Cons

Getting into Microsoft can be hard. Make sure you are thoroughly prepared and have done a lot of research.
Sadly, the parts of Microsoft I saw have a lot of politics. Tread carefully, and ask others more experienced than you for advice.
Teams or groups tend to work on overlapping tasks, therefore you have to fight for your patch and, sometimes, it isn't about getting the job done right, it's about getting it done first, and publicizing that fact.
Because teams are graded on a curve - 10% lowest performaners, 70% in the middle and 20% high performers, you are effectively competing against your own team throughout the year. Make sure all the managers in your group - not just your own - know about your achievements.
Reorganizations and restructuring are the order of the day at Microsoft. Learn to go with the flow as the change happens and create a new niche for yourself when the dust settles.

Advice to Senior Management

Management should stop constant reorganizations. They are destablizing, costly and negatively impact customer experience (both internal and external customers). Even a radical move, like freezing all reorgs for two years, would be a good idea. People need to win the battle, not constantly rearrange troop formations.
Management need to take a hard look at their marketing and advertising strategy. Uncool advertising is so embarrassing for employees, who'd really like to be proud to work there.