> where I expect the exact same look and feel regardless of the underlying OS

Slightly ironic, as I think a new UI is underway (and coming soon?). Not sure what version it's planned for, but I think some beta has it enabled by default already, was surprised when I saw it. So the consistent UI is here today, and will be in the future, but there will be a slice of time where different users will run different versions where some switched to the new UI, and some haven't. But it'll hopefully be a brief period, and of course it's still cross-platform :)