After flashing the phone in February, I have use the phone now last week during holidays. Looks fine so far. The phone has a very bad performance (e.g. GPS navigation via Google Maps is quite unusable). But no nags, no pupups, no unwanted software.
I have updated firmware some weeks ago. But honestly, I do not use the phone at all, exept from some rare occasions when I need to check something with an android phone. So far, I did not recognize an unusual behaviour.