Microsoft has just released an update to its Reader app in the Windows Store for PCs. The app is bumped to version 6.4.9926.18190, and according to the changelog this update will improve reliability and address data loss issues.
If you don't want to install a Win32 app like Adobe Reader, this Reader app from Microsoft is a good lightweight tool that can open your PDF, XPS, and TIFF files. More than that, the app also makes it easy for you to quickly return to files you've recently opened, search for words or phrases, take notes (also with Surface Pen), fill in forms, and print or share files.
Please note that this is not a universal app, as Microsoft also has the PDF Reader app on the Windows Phone store, which has less features. We don't know yet if Microsoft plans to release a universal Reader app for all Windows 10 devices in the future, but it may be a good idea to finally have the same set of features on both platforms.