Like @jock1092 said, there're some changes in the interface, but it doesn't take that long to get used to them, especially if a) you're comfortable using PCs, & b) you've been through interface changes before (i.e. switching from 3.1 to 98, from 98 to XP, from XP to 7, all of which I've done).
I would recommend that, if you want to upgrade, you do so within the next month of so. IIRC, the timeframe during which Microsoft is offering the upgrade for free runs out this summer. Plus, the major update that they're planning for this summer will only be available "for free" to those that already have Windows 10 installed.