If you have a phone and PC with Windows 10 installed, if you set a reminder, it will show up on both your phone and desktop. The same goes for places as well; if you add or remove a place on one of your devices, it will sync across all devices. However, we should point out that 'places' will sync to a Windows Phone 8 device too but 'Reminders' do not.
While this functionality seems obvious, and was expected, this functionality shows the power of Microsoft's ecosystem and by using a Windows 10 phone with your Windows 10 desktop, there are tangible benefits that are not possible when using an iOS or Android device. That is, of course, unless Microsoft finds a way to bring this functionality to other platforms - and seeing how they have gone fully cross-platform for nearly everything they do, this wouldn't surprise us.
We are still playing around with Windows 10 for phones as we suspect there are quite a few more features that were not announced that are built into this release. If you happen to find any, make sure to send us a tip.