I can confirm that the "critical update" was indeed Denim, I'm now running the latest and greatest official release on my 635.
For those keeping track of the worst update in history so far: Lumia 635 CV Germany, Vodafone branding, no sim- or netlock, Region & Language USA.
I now have live folders, NTP, as well as some other improvements brought forth by Denim. Can't tell whether or not performance has improved yet.
I am in the US, have a Lumia 635 on Cyan with AT&T service and am hoping for a Denim update. It seems that AT&T decides when we will get updates. Does anyone know if there is a way to find out from AT&T what their rollout plans are for various phones and updates? They told me in an "online chat" that they had no plans to update the Lumia 635.
What I mean by this is the stupid fragmentation of Denim. Coming from the Apple ecosystem I'm used to "this is iOS version X, it will be release for all supported devices on this and that day and this is the list of supported devices". And sure enough that very day the new iOS version was available for all supported devices in all countries on this entire planet. Microsoft seems to have a rather different approach and quite frankly it seems stupid, pointless and terrible. And while I'm currently not residing in the US this carrier dependency is the very reason why I never purchased a carrier-supplied phone but always made sure to get the free market alternative (btw, why does this never seem to be an issue with Apple anyway, only with Windows Phone and Android?). I realize that this is very different in the US, with Sprint and Verizon having locked down their network to be used with their phones only - it's always easier to argue from a European perspective since we don't have stupid stuff like this over here :wink:
Anyway, back to topic. Yes, the Lumia 635 in Germany did get the Denim update. Almost a shame that I have replaced it with an 830 more than a month ago which, coincidently, received the full Denim update on the same day.