I have been mining Monero and Electroneum for a little while now, and it's been interesting to say the least - particularly with regard to Electroneum.
I had started mining Electroneum before the Monero fork, and once the Electroneum mobile miner came out I was a little chagrined to realize that it actually generated about the same rate of coins as my GPU efforts. So, I quickly dropped the GPU mining and switched that effort to Monero.
The mobile "miner" is actually just an "air drop" rather than actually mining anything on the phone hardware, which is fine by me. As long as some coins end up in my wallet, I am good.
Electroneum has been going through a lot of growing pains too, and although they seem to be heading in the right direction at last, you never know with this world of cryptocurrency. Do they actually have the tech or the smarts to pull this off?
The concept of being a device to assist mobile transactions sounds great, and there is a good bit of enthusiasm around the product - but it's hard to tell yet if they are reaching beyond their grasp or not.
Once again, I am glad I don't invest heavily in this sort of stuff; I don't think I could stand it if I had big dollar amounts involved!