As I have discussed elsewhere, previously, there is less necessity to add certain software, plug-ins, utilities & such w/ Windows8. Between it & what is or will be current browsers (like IE10) a lot, that wasn't, native, now is. In many cases things, that act as apps, are seemingly redundant since, they could be had, still can be, in other ways & presentations than, 'Metro Style' applications & what could be tiles on the Win8 Start screen. There has been lots of discussion voicing both that taking the APP route is (more) appealing & that it is not. Of course, in the CP, we weren't sure how far along APPs were & waited to take another look in the RP. The opinions included the .pdf reader.
Pre-Win8 a PDF reader was required to be added to the OS. W/ Win8, a PDF APP is native. I do feel there, still, is a place for Adobe Reader (let's say) w/ its features/tool-set. However, upon a second, deeper look @ the OS Reader, now that it is w/ the RP, it does have appeal. The appearance (display) is clear, clean, uncluttered, 'pleasant' visually AND things get nice, slick & smooth when put together w/ what's on Charms. Whether printing, E-mailing & more the offerings, the 'look & feel'. Depending which gets to feel comfiest or what one is wanting to do, @ the moment, w/ a .pdf, the native reader is a pretty appealing additional option (CHOICE) and worth checking into it.
Cheers,
Drew