Adobe themselves have now released a PDF reader for Windows Phone. Yes, there’s been an MS version, but this is the official one from Adobe. You can open and read PDF documents and you can also search, copy, paste, zoom and scroll around a document.
It’s good, but it doesn’t seem to offer sharing, so you’re not able to share by Bluetooth, NFC or email etc. Bit of a shame that, so you have to use the Microsoft PDF app instead. Still, it’s free and you can get it here.