People were waiting for the 5" phones with 1GB RAM and Firefox OS 2.x (e.g. ZTE Open L)
A big mistake was to go too much low end then fail to release upgrades fast enough. People were stuck on version 1.3, which doesn't actually offer privacy - no adblocking and no filtering. For those that were interested on technical and security grounds, it was a giant Osborne effect (that would still be going on : Web Assembly and Servo are not there yet). It did have e10s early on.
The best part is the phone didn't require an online acccount, nor even asked for one.
With today's phone CPUs it would be a kind of Chrome OS for the mobile phone.
The one low end friendly aspect was the OS and built-in apps used very few storage. Security patches were small and quick. (But actual upgrades required to download a community image and to mess with the phone, using a Windows program to flash it. Hence the normal end user experience was to run Firefox OS 1.3 forever, based on Firefox 28)