IMHO it was a worth bet. Had it succeeded we could have one extra mobile OS with much more freedom today. It lost steam, but it would be a shame if not even attempted. It lives through FireOS, despite negligible market share. And I still have my Alcatel One Touch Fire as a keepsake.
Huge missed opportunity for the Mozilla-Yahoo partnership in my opinion. I was intrigued by it at the time, but I think I recall opinionated bloggers on the subject that what it needed was the bare bones, features like maps and an email client and so on. And Yahoo was still at a point where it was relevant enough that it could have pitched in on this front, although that would have required strategic vision that Yahoo never had. A big risk, but the right kind of idea.
It's the kind of paradox of all of these Mozilla criticisms. "Do something to diversify your revenue. No, not that... Not that either."