This means that Xperia M owners can now move to Android 6.0.1 Marshmallow through these official nightlies. The update is reasonably stable with most features working. If you are an Xperia M owner and want to give this a try, you will need to make sure you are running Android 4.3 Jelly Bean firmware and have an unlocked bootloader with a recovery installed (either CWM or TWRP).
If you are an Xperia M Dual owner, then unfortunately you won’t be getting official nightlies due to a known data bug that affects the second SIM. However, there are patches available to help enjoy this latest update (see the XDA source link below).
Via XDA.
Thanks Aashish!