Yeah, Google strikes me as first and foremost an advertising agency. They make their revenue from ads, and ads are not really the sexiest thing out there IMO. They do a lot of interesting research and large-scale implementations in the pursuit of advertising revenue but the bottom line is still going to be the bottom line, and other types of work are going to be better for a lot of people.
the largest reason why I don't think I'd fit is that everyone there seems to think that google always does the right things, or at least, acts for the right reasons. The degree to which everyone who works there seems to say that it's perfect implies that there is little tolerance for recognising the bad parts of the company, which I think is quite dangerous to the company (and it would be stressful for me as an employee.) Hell, I say bad things about the company I own. I think examining the downside of the choices you've made in the past and the choices you are making now is extremely important; and I think if you believe that you always do the right thing, you are deceiving yourself.