I did not affect my linux partitions when I upgraded form 7, grub was still there and everything was fine. It's not bad, it functions fine, but I regret upgrading. Windows 7 was much faster to boot and be usable and I didn't have to worry about making sure that I did a complete shutdown "shutdown /f something something i forget(I made a batch script for it)" to make sure I could access the shared data storage partition in linux. That is how they get those fast boot times, it doesn't completely shut down. Booting back into Windows after the complete shutdown takes fucking forever, and then you still have to wait for it to load all the other bullshit before it's usable. IMO stay with Windows 7 unless you have needs that only 10 can cover.