Microsoft

This is specifically for the Online Services Division and Bing Search in particular.

• Very smart people.
• Lots of projects to work on, so technically it's possible to transition to a team you think you can be more productive, though this is not very encouraged.
• Very smart managers that don't micromanage.
• Modern technologies (latest versions of C#, Visual Studio, and frameworks).
• Huge scale that makes it possible to uncover some of the bugs in .NET/CLR itself.
• Separate offices.

• Working on a tiny part of a huge project doesn't help to feel ownership and limits the amount of learning.
• Some decisions are driven by politics and from the top, which leaves engineers to pay for management games.
• Source version control makes it very hard to have multiple local feature branches. This noticeably decreases productivity.
• Perks are very average, especially when comparing to Silicon Valley companies. These include rare offsites to the cinema, coffee machines, and much appreciated foosball and pool tables.

Consider using micro-service architecture. This will give engineers a sense of ownership and a bigger surface area. They would be less dependent on the errors of other teams and would be able to learn and innovate more.