Blake Ross, one of the original FireFox developers, says that Google has lost his. Paul Thurrott ask Blake what took you so long because he has been banging this drum for a while.
Me? I mostly trust them for search, but the example Blake gives of putting ads for Google's own apps at the top of the search results without it being a search result really bothers me. The IE7 toolbar lockin is crazy, I chose to use the toolbar and your search Google, it doesn't mean I don't ever want to change. The privacy policy on the phishing filter is troubling, and privacy concerns is why I don't use GMail. I don't want ads in my mail, and I don't like the potential to have my mail mined whenever Google feels like it now, or if they update their policy.
That is one of the reasons I keep re-upping my .Mac account. It is reasonably private, and I have pretty control over spam. The other .Mac benefits sweeten the pot, but the easy publishing and OS X settings synching is extremely nice.