I have not encountered any software compatibility issues with W10. W7 is already 7 years old. It was a great OS, but it is a dinosaur now. W10 is more secure right out of the box (reason enough to use W10). It is faster and knows how to work great with and properly maintain SSDs without the need for any 3rd party software (like Samsung Magician, for example).
I figure if there is some legacy software not supported in W10, I blame the software developer for not releasing an update and would start shopping around for current alternatives.
That said, in terms of legacy software, I'm still using Office 2007 and Outlook 2007 and they still work great (and fast!) in 64-bit W10 Pro.
Most have to do with the start menu and shortcuts.
Then I recommend
Start10 or
Classic Shell. Start10 costs a whole $5 but IMO, is well worth it. It has a 30 day try before you buy period so I suggest you try it and see. Classic Shell is free and also very popular and well liked. And while it works fine, Start10 seems to be a bit more polished and refined to me, something I expect in a paid product.
Oh, and for sure, if you don't like how the traditional Microsoft games (Chess, Freecell, Hearts, Solitaire, Spider, etc.) work in W10 (or W8), no problem. To get Windows 7 games to work in Windows 10, see
Get Windows 7 Games for Windows 10. Ignore the "RECOMMENDED" link to fix Windows. That's just an ad for the free site to get some revenue for their efforts.