This outcome should have been obvious to everyone involved. The fact that it wasn't raises serious doubts about the Mozilla leadership. You can't compete with Android by being slower, less responsive, and ship with less features.
Seriously... I avoid Firefox on my (rather beefy) desktop because of how much it freezes. I don't want to imagine how it worked on a 50€ phone, which looked like it was their target. Maybe they thought Gecko would be ready by the time the OS was going to ship?
The one downside is that it's memory-hungry, so on my very underpowered phone, it gets pushed out of memory a lot when switching apps. On a more powerful device I'd never notice.