If there was to be any market interest, I thought their targeting and marketing efforts like this were pretty spot-on.
(Not implying there is any correlation between those two last facts.)
I live in Poland and I was lucky that I could easily find a cheap FxOS phone, which actually I am using now. This is the only truly private phone available here. It is a pity that Mozilla abandoned it. Bigger pity is that people do not give a sht about their privacy and open standards.
The feedback I received from the people that tested the platform development wise was that they had not built it yet.
So that explains the lack of marketing.
Somewhere in the FF OS 2.x series, an upgrade seriously made the keyboard unusable, and I never knew where to turn for bug trackers / support. I had also tried to make IPv6 work, experimented a bit with the app system.. I'm an average programmer, but I participate in a few large projects.. Firefox has always been a mystery to me, with lots of code names and hard to use bug tracker.
Huge fan of Mozilla otherwise, so hurts a bit to say this.. other than that, it was a functional phone for 2 years.
"If you build it they will come" isn't a valid benchmark when there's already two options with massive market share that consumers are more or less happy with.
(Since it's talked about in some replies, I live in the US).