Moved my machine to Windows 10 today. It took a couple hours, and been going through the things I'm using to see what may be "broken".
first thing I saw was in Eclipse Luna. I was used to editing a .mc in a tab, and the hitting "Alt-F, then S" to save it, and then running it. The "Alt-F" no longer allows a "save". You need to use ctrl-S instead.
Not sure what happened, but after staring the simulator, everything in it's apps\data directory was gone (this could be that windows had just blasted the "temp" directory and not a simulator issue, but a reason to save off your test Object Stores before you upgrade.)