Google is not what I would call an adversary. Mozilla, Google, Microsoft and others are willing to go in the same direction, they don't share the same priorities and it's all about negociations and stuff.
When Mozilla and Google renewed their partnership, I heard that Bing was ready to pay Mozilla a bigger check than Google was, yet they choose to stick with Google because they thought it was a better option for the user. If it's true, I think we can trust them about the way they earn money and use it.
On the other hand, as far as I understand, Firefox OS is built with partners from the industry, which probably means that development costs are shared, and not only supported by Google's money.
Last but not least, we probably have a lot of different experiences with firefox, but my setup does not crash every so often...
When Mozilla and Google renewed their partnership, I heard that Bing was ready to pay Mozilla a bigger check than Google was, yet they choose to stick with Google because they thought it was a better option for the user. If it's true, I think we can trust them about the way they earn money and use it.
On the other hand, as far as I understand, Firefox OS is built with partners from the industry, which probably means that development costs are shared, and not only supported by Google's money.
Last but not least, we probably have a lot of different experiences with firefox, but my setup does not crash every so often...