* Limited upside compared to a start-up. You don't come to Google thinking you're going to strike it rich in one fell swoop anymore. This is the price of stability.
* Company has grown quite large. There's something intangible that changes with growth, and even getting to know everyone in your extended team can be hard. There are no all-company events anymore. These have been replaced with organization-specific events.
* Management quality varies. I have a great manager but I've heard horror stories.
* Your initial project is assigned based on expressed preferences and relevant experience. It may take time to get off of it if you don't like it.
* Ramp up may take some time, but don't get discouraged as this is expected. The software stack is almost all in-house and so there's indirect transfer to other systerms.