Hmm, let's see...
- Apps being able to add sections to settings - I know it might sound stupid, but it also makes sense to an extent.
- Major overhaul of Settings - let's have some sections (Personal, Device, etc.) paged apart, so that the options are easier to find
- The Email app from W8/W8.1. I hate how all my accounts are spread around the app list, why can't we have one app to handle them all? The W8 app does it so nicely, and we could even sync accounts with that...
- Further control of the main screen and the app list. Further tile sizes (3x1, 3x2, 2x2, 1x2, in WxH format), option to disable the alphabetical listing in the app list. Also further control over the live tiles (e.g. custom layout live tiles, like Cortana's, etc.).
- Better networking. Now we have VPN, but I still miss some features that are for Windows - Home Groups, accessing network drives, further networking tools, PROPER NETWORKING API (seriously, no app can access e.g. the list of available WiFi hotspots???)