It works fine in Firefox, I do it for the intentional isolation. To me, chrome browser is "google browser"
Almost everything runs just fine in Firefox.
Google software seems to be chrome-optimized, but it's usually only slightly slower on Firefox - it still works.
Some google websites are chrome only because of the use of some non standard plugins.
Do you have any details of which ones? I have not discovered any so far - everything seems to work just as well in Firefox (e.g. gmail, youtube, search, maps, adwords, adsense, analytics, cloud console, webmaster tools are the ones I requently use on Firefox with zero issues)
Google earth and Google hangouts
It works, but it uses non-standard extensions that are only present in Chrome, so it runs slow in Firefox, especially since their latest update.