I have a 4K laptop, Lenovo Y50, that came with 8.1 but has been running 10 for a couple of months now. I find the scaling a little better in 10 than 8, unfort for the OP it never ran 7 so I can't compare it to that.
I haven't had with any Microsoft menus or text so far, the only problem has been the command prompt which won't scale at all and is incredibly hard to read. I could try using PowerShell but I don't know cmdlets by heart and on a gaming laptop my command usage isn't all that much.
Most of my problems have been non Microsoft applications. A lot of the screens in Steam are not crisp. And I game at 1080P but the Steam interface runs at 4K in game so that ends up incredibly tiny. The reverse happens for GOG where their new Galaxy program won't scale up but their in game interface does (or or more likely it just stays at HD so it looks normal).
I'm using the Larger (150%) setting. I haven't tried the custom DPI as BW suggested since, for the most part, it works fine. I might try it though just to see what difference it makes.