Version 11.0.0 Adobe XI, Windows 7. All the points below relate to viewing PDFs in Firefox.
1) Resolution of PDFs is terrible when viewed in browsers.
2) Text frequently randomly vanishes and comes back in a strobe-like manner making reading impossible. This occurs as soon as the document loads and continues until I refresh the page.
3) When zooming in on PDFs to read the document (necessary because of the awful res) large blocks of text vanish.
4) Printed resolution is also awful, text lacks crisp, well defined edges.
5) It crashes my browser. A lot.