Well here's a tip, unless you have the time and made sure that all of your data (that is important to you) have been backed up, skip updating to M for the meantime. 
I had just finished updating my ZE551ML by going through the FOTA thinking it was ASUS finally rolling out the official M, got a bit downplayed after seeing it was a security patch for L. While still hyped over the false-positive, I went ahead and braved the manual update following this Tutorial (best tutorial I've ever seen here so far) here. A couple of minutes and a few restarts later, was grinning like an idiot and liking the over-all experience! All my downloaded apps worked fine and was already on the last stretch of checking and making sure that everything was OK.
So I decided and get a selfie just so I can post that I finally got the M, then it hit me: "The Camera has stopped responding."
After going through all the efforts and voodoo conjuring I could come up with, I am now left to the very sad part of going through a Factory Reset. Although it is now "attempting" to revert all those previously installed (Google saved) apps, all those settings and customization's are now flushed down the ASUS drain. yey.
For those of you that have yet to decide, you have been warned. My 2 friends (with the same model) got their ZE550ML's ported to M with different case scenarios, but so far was OK. I guess I just draw the short end of the straw on this one.  |