If a dependency changes rpmdiff reports all dependecies as added and removed,
even the ones that did not change. For packages with tens of dependencies this
kind of output is unusable.

To show only the parts that really changed I use an additional filter:

#!/usr/bin/ruby
removed=[]
added=[]

def addremove itm, add_to, rmv_from
    if rmv_from.include? itm then
        rmv_from.delete itm
    else
        add_to.push itm
    end
end

STDIN.each_line{|l|
    lremoved = l.match(/^removed     (.*)/)[1] rescue nil
    ladded   = l.match(/^added       (.*)/)[1] rescue nil
    if ladded then
        addremove ladded, added, removed
    elsif lremoved then
        addremove lremoved, removed, added
    else
        puts l
    end
}

removed.each{|r| puts "removed     #{r}"}
added.each{|r|   puts "added       #{r}"}

Please consider integrating this functionality into rpmdiff itself