Pros: Developers have their own offices. Because Microsoft has a longer release cycle than many software companies, the stereotypical "have to work overtime because the project is due" doesn't really apply. It's a very laid-back environment. As long as you get your work done and don't miss meetings, no one really minds when you work.

Cons: As with any company with thousands of employees, sometimes you can feel like a grain of sand on the beach. As a developer, you don't have a say in the big picture of the company. If that's important to you, don't work here; find a start-up.

Pros: I get to work with intelligent and supportive teammates every day. Amazing facilities and a gorgeous landscaped HQ. Work/life balance is very good for most SWE Interns I know. Free drinks. They bring in good musicians to play over lunch at the main cafeteria. Performance feedback is not only focused on individual contribution but also on how well you work with others. I've been told this really improves the company culture, especially on the main campus. They make an honest effort to give interns projects that are interesting and within the scope of a summer. Top-notch health insurance, even for interns.

Cons: The culture of different teams can vary. (I have heard good and bad from other interns.) Microsoft always manages to stay in the news with the latest PR gaffe. (Honestly, more amusing than upsetting to most employees.)

Pros: As one of the world's largest software companies, you feel that what you are doing there is making a difference. The work is challenging and interesting, and the rest of the staff is made up of very bright people willing to help you. It also has a very fun and laid-back environment. The free drinks are awesome, though they may make you gain some weight if you abuse them.

Cons: Your success as an intern depends a lot on which product group you're on; some managers are much more demanding than others.