This report goes into details about issues with WANs, the problems inherent in application delivery, and more. It is available free though registration is required.
"Wide Area Networks (WANs) and enterprise bandwidth costs have continued their ascent as a result of businesses deployment of applications. Aberdeen's benchmark report, "Optimizing Application Delivery over the WAN", found that the top obstacles enterprises face in ensuring seamless delivery of data to end users are: increasing amount of rich content (40%), increasing TCP traffic (41%), and "Chattiness" of currently deployed applications (43%). Traditionally low-bandwidth remote office WAN infrastructure performance is challenged by emerging applications such as Virtual Desktop Infrastructure (VDI)."