Paper and pixels as a medium do share some very basic common elements; they both attempt to convey information and provoke a response. However, the fast pace of the World Wide Web makes it difficult to share information and ideas if they are presented in the way they would have been presented on paper. It is important to remember that most people who surf the web are looking for an easy way to find the information that they need and they can be highly agitated by any fluff found in a paragraph.
When writing on the Web it is essential to use headings and plenty of spaces between paragraphs. These two techniques make the document easier to read and navigate. Links and attachments are also ways to include additional or further information in a clear and concise way. Pixels are definitely the way to get your ideas out quickly to a lot of people.
Paper, on the other hand, still has strength that make it the better medium choice. Subconsciously, most people consider paper to be the more formal of the two mediums; invitations, proposals, and announcements are received as being more sincere and meaningful when presented on paper. When using paper you can easily add a personal touch that makes the receiver feel that they are important to you. This is possible when using pixels but it definitely take a little more effort.
Both paper and pixels can be used effectively if they are presented in a way that is appropriate to the medium.