Like always i informed you before time about JB OS, yet there is an issue with JB OS which Q fellas are trying to resolve after a week than will officially launch for update yet the method unknown how but hang on for a week.
Atleast one thing is clear that update is available now i think they are customizing JB with Q apps and all which are useless but like this modifying original OS mess up.
Lets see one week they said as update came ill be informed and will update you all about it.
Many asked me question about 512 MB and JB OS so my answer is it will work flawless even benchmark result is gonna be better. Battery timing efficiency animation are improved in JB so nothing to worry about .
We all have waited almost 4 to 5 months one more week as far as i think it will be free update kindly hang on and do not upgrade by yourself because A10 been upgraded but sensors dont work so wait for official update.