I upgraded to Windows 10 two weeks ago. I was on Windows 7 and using DisplayFusion and very happy with what it offered. Since Windows 10 has some nice dual monitor support I almost decided not to use DisplayFusion again.
But after 2 weeks, while Windows 10 allows a taskbar on each monitor and has better integration (it allows to move Windows Win+Shift+Arrow to other monitors) as well as resizing and snapping them with shortcuts, there were some things annoying me. Hitting the Win key always opened the menu in the main monitor, not the current one. I also missed the ability to middle-click on application titlebars to send them to other monitors and I could not pin apps to taskbars on the extended monitors.
Windows 10 is better but still not great for multi-monitor users (I have 4). I installed DisplayFusion and I'm happy to see that I can still use all the native Windows shortcuts for Windows, so DisplayFusion is not messing with anything or removing features, but adding more things on top of what you already have in Windows 10. It's a win, win situation.
-- Volker