It takes so long for Adobe to load etc., Then once it loads you have to zoom out, scroll between pages instead of clicking between them, etc. The trend of viewing pdfs in scribd is a good one from my perspective.
And Scribd just sent me 10(ten) e-mails since I had the audacity to log in using Facebook and it decided to go all social on me and add all my friends one by one. No thanks.
Instead, you should just offer the PDF for download, and alongside it include links to some of the alternatives than can permanently relieve you of Adobe Reader.