After many days of testing the new firmware, my favorite feature is the AutoISO. I have been using many different cameras for about 15 years, but it never occurred to me to have a requirement for this feature. Now that the M8 has it I realized how useful it is. For long time I have been working in full manual modes (even on dSLRs) and found it annoying to go to the menu to change the iso if the light levels were not sufficient. Obviously, I don't want to adjust the aperture and shutter speed setting which I want for a certain situation. It is interesting how an automatic feature like the auto ISO is actually enhancing the full manual concept on a camera.
For me it is a huge improvement.
As for the noise improvement, I am not sure about it if there is a change. But I never worried about the noise level (160-1250 ISO) as I like how Lightroom cleans it up and what is left of the noise reminds me to film grain which is to me means an artisticly enhanced photograpgh.
The next big improvement is the ability to use the SDHC cards. Now I can go on a trip with my M8 with 30GB.
Miklos