A few things come to mind, but mostly related to Google 'today' not being the little underdog it was 15 years ago when it started, it's a giant corporation.
You are probably employee #sixdigits counting everyone who's no longer employed and #50000-and-something for current employees and that just isn't as prestigious even if their standards haven't changed.
They make a lot of unpopular decisions - most things with google plus, no more free google apps with your own domain, significantly changing app engine pricing, reader and the long list of other dead services that collectively spell "be careful" even to their most vocal fans - the tech industry who made god knows how many millions pandering to Google and Google fans openly mocked Keep's launch!
To counter that they offer perks and they work on some really cool stuff and they still have a reputation for hiring smart people ... but all of that is normal for any startup today.
I would guess (but don't know) that a similar transition happened for HP, IBM, Oracle, Sun, Microsoft, PayPal, eBay etc as well when they finished puberty. I would be somewhere between indifferent and disappointed if one of my friends settled for a job at any of those companies.
It's great if it's your dream though.