Back in October I recommended that you not upgrade to Windows 10. There were too many problems at the time. In November Microsoft put out a patch to Windows 10 to bring the version number to 10586. This version of Windows 10 seems to be very stable and worth upgrading to. I now recommend you upgrade to Windows 10 before July 29 at which time the upgrade stops being free.
There are visual differences between Windows 7 and earlier versions of Windows and Windows 10 but it’s not so bad you won’t be able to use it. There are also tweaks you can make to Windows 10 that make it more user friendly.