The last time I've checked, the worst thing was that it demands money once the document is old enough(!) Then, it required from you to have an account just to download the document. Finally, it didn't work without Javascript. For me, instead of adding value, it reduces it, so I decided to avoid it to save my time.
Not just Javascript but Javascript from about a dozen different hosts last time I tried it and quite a few of them seemed to be required. I avoid it too.
I know Scribd is a Y Combinator's company.