My only complaint on Win10 is, as you have mentioned, the telemetry and its attempts to bankrupt me through massive, unexpected updates. For the most part that's manageable through options, though I still suspect every now and then it downloads a large update secretly (my bandwidth useage can be very consistent for months and then out of the blue I get the dreaded "You have used 50% of your bandwidth" message with 25 days to go.)
Oh, and the horrible Metrosexual UI, which can be
easily replaced with Classic Shell 