The big reason I'm holding back is that they force driver updates on you during the upgrade from 7->10. Video drivers in particular. NVidea's new drivers do not support their older cards, I found this out when I updated the video driver on Win 7. I have two video cards, one fairly recent and and older one that I use to drive an older monitor that I use for a browser window(I have 3 monitors--I'm a photographer and Photoshop works better with multiple monitors). That one died with the update. I had to roll it back.
I believe that they now will let you delay a device driver update for a couple weeks but then install it whether you want it or not. That's the last I've heard anyway and they may have changed it. This applies to all drivers not only video.
I did a quick search on win 10 and office 2007 and it seems to work fine.
So if you are sure you can survive the driver update you may be fine upgrading. You have until the end of July, maybe longer since the number of people upgrading has been way below what MS wants.
BTW if anyone out is tired of the constant nagging, install GWX Control Panel. Google it to find it. It's free, it blocks updates, and it has a small foot print on your system.