Pros
Micrososft has great benefits, reasonable pay and high quality people. It's diversified line of products and offerings makes it fairly easy to shift technology or business focus without changing employers. The company really bends over backwards to ensure good working conditions and an atmosphere of respect. Career advancement is strongly based on merit.
Cons
In general, the company is suffering from a lack of strong senior leadership and vision. Established divisisions such as Office tend to be highly conservative and bureaucratic while divisions such as Online Services tend to be basket cases of shifting directions and priorities. Cross-divisional politics and a Microsoft tendency towards designing complex and grandiose systems tends to sabotage many promising cross-company initiatives.