Whither rejection letters?

An old school rejection
Credit: The Pulp Magazines Project

What has been your experience with rejection letters or notices? It is the broad consensus of readers
of this blog (I believe) that people prefer to be told, than not to be told, that they did not get hired for a position. If I had to summarize people's ideal rejection process, it would be:

• as fast as possible
• personal, not generic
• not too familiar, not too cold
• it would offer reasons as to why they were not selected (unlikely, I know) 
• ways to improve (same)

Readers, your thoughts?