Consider the 2 stars the pity for the fact that you started with a great concept and then ruined it with greed, lack of innovation and so much bugs that never get addressed. There is non-existent support and utter silence from the developers which means this is nothing more than a money grab or to make something to sell and they care nothing for its quality, reputation or functionality.

The FX addon as been broken for so long without any action that it has become a useless garbage that won't save any settings, keeps prompting for the E2E password and won't retain anything. It is a constant annoyance which far outweighs any worth. Another promising vision ruined by incompetent developers lacking any integrity or dignity.

You are replaceable by open source, clean, functional, efficient and TRULY FREE solutions that don't have so much gimmick (features that were free but now paid because they ran out of things to innovate) and play with their users (offering quota for referral and then giving you nothing). You showed your true colors very early on, which in a way I thank you - better to know now that you are unreliable and untrustworthy than later.

I won't mention the other immensely superior solutions because my review and the complaint about the software is legit and I don't want anything to distract from it. You can simply search for alternatives to this failure and find them in spades. I will however say, avoid AirDroid, they are woefully compromised, even in that condition they are superior to Push.

/EDIT: As of 56 this addon completely breaks, won't load anything at all and cannot even be reinstalled as Mozilla considers the package corrupt. So pathetic that after all this time knowing there is a problem with it and didn't fix it, now they just let it die altogether; if they have no respect for their own product why should anyone else frankly. They have effectively abandoned it and that shows their lack of integrity and makes them utterly untrustworthy.