Google's problem is that most of the work is shitty legacy maintenance. If you can get on one of their machine-learning or research projects and have a good manager, you'll have a fantastic experience (and I say this as a notorious Google detractor). Take the offer seriously but negotiate extremely hard on project allocation because it's really hard to transfer to a good project if you start in the wrong place, so your first project is the difference between an awesome Google career and shit. And most people get shit. Good luck!
ETA: Google would be awesome if it adopted the Valve culture where employees are trusted to allocate their own time, but I wouldn't hold my breath.
ETA: Google would be awesome if it adopted the Valve culture where employees are trusted to allocate their own time, but I wouldn't hold my breath.